991.1 Bore Scoring
 

Has anyone heard of any cases of bore scoring on the 991 engine? Dropping off my car with my indy for the change over valve job, we were talking about the 997 and 991. He said he had a couple cases of bore scoring in 991's in his shop.

Yes, I had it in cylinder #4 at about 18K miles. Started as a faint ticking sound, like a dry lifter. Dealer said keep driving it. After a few thousand miles, it got louder and started consuming oil at a rate of >6qts every 10k miles!!

Dealer finally pulled the spark plugs and #4 was black and wet with oil. Borescope showed significant scoring in just that cylinder.

I ended up getting a completely new engine at 23k miles. Completely covered by CPO warranty. Whew!

Dan

BTW, mine is a 2013 C4S with PDK. Always driven pretty gently. Tracked once for a total of about 40min.

Dan

Does anyone know if this bore scoring stuff has been fixed for good atleast in 991.2 ? (all that alisul/nikasil and what not).

When was the ticking sound most apparent?

I have not heard anything about the 9A1 engine and bore scoring. Charles Navarro hasn’t seen it either according to Panorama, March issue, page 90! Do you have pictures of the plug or a bore scope to share?

Tampa991 - ticking was apparent at idle and gentle initial acceleration. Above about 2300rpm it couldn't be heard.

Dan

Alisul/Nikasil hasn't been used in quite some time - 9A1 have cast-iron bore liners, 9A2 is Rotating Single-Wire" (RSW) iron coated lining, which I have read is like 3-D printing on the cylinder head and supposed to be very robust.

sean

9A1 uses Alusil bore lining per Flat-6 and many other sources. I had slight bore scoring confirmed on my 997.2 (9A1) that consumed about 1liter every 1500 miles. Just did UOAs to stay on top of wear and aluminum content to make sure it wasn’t getting any worse and kept topping up until I traded in for 991.2. Drove it like that for 5 years.

https://rennlist.com/forums/997-foru...l#post14570999

It exist. Not as bad I’d say as M96/97 but I’ve talked to more than one or two that’s tore into 9A1s. Here’s a good read - https://rennlist.com/forums/997-foru...l#post14573451

I stand corrected. I thought Porsche had made the change after the M96/97 Series.

Here are some photos from when they discovered the scoring in my 2013 991 C4S. I also have to correct myself, it was cylinder #1, not #4. You will see attached a spark plug from #1 (very black) and #2 (clean). There is also a photo from the borescope showing the scoring in #1.

Dan
https://cimg1.ibsrv.net/gimg/rennlis...90b3afbaf0.jpg
https://cimg2.ibsrv.net/gimg/rennlis...c82e5ef5c6.jpg
https://cimg3.ibsrv.net/gimg/rennlis...46b92070b3.jpg

Here is a 9A1 from a 997.2...still havent heard many cases of the 991.1 though..likely because we haven't had enough miles build up in this generation.

https://www.youtube.com/watch?v=02HxKanh-JY&t=324s

Must be a rare issue in the 991 platform. I had my spark plugs changed at 33k miles on my 2013 991 3.4 and they were clean as a whistle.

Wow, it just amazes me, Honda and Toyota can build pretty much bullet proof motors but we have these crazy odd issues with just about every generation of 911. Okay before pounding, yeah I know these are high performance cars, and I am a 911 fanboy, but still, at this point you would figure they could get past these crazy things like PDK bombs, IMS/RMS, bore scoring. Now with that said, my 911 is going nowhere.

So, what caused the scoring? Piston slap? Leaky injector/preignition-related overheating?

Agreed, I'd like to know the root cause and how to avoid. Is the only fix literally a new engine? And is that appropriate under warranty but outside of it is it safe to live with and what precautions does one have to take when they have confirmed scoring?

Three primary things (IMO) contribute to bore-scoring:

1. Cold oil (people screaming the motor before the oil temps are 180 degrees or higher)
2. Use of Mobil 1 vs. a Good oil like Motul
3. Cold climates in conjunction to the above

One theory - I believe the main cause of bore scoring is due to DFI where the injector could be compromised and be spraying too much fuel...this causes the lubricated cylinder wall to be washed down and metal to metal wear occurs over time.

can you elaborate?

and is there anything within our control or preventable in the regard? lol

Thinner than other oils of the same grade.

Greater burn-off than other oils of the same grade.

Piston-slap observed/noted with long-term use.

Increased valve noise compared to oils of the same grade.

Greater thinning-out/inability to stay-in-grade during use.

Poor performance on the Timken test (tri-synth)

https://secure25.securewebsession.co...ball_large.gif


In my 997.2 with Mobil it use to burn about ~1 quart every 1,000 miles. Then I switched to Motul 8100 5W-40 xcess, didn't burn a drop, ran quieter, and felt smoother. 991 since day 1 Motul 5w-40, doesn't burn a drop, runs like velvet smooth brand new motor.

Don't believe the hype. PM me if you want a dose of reality w.r.t. Honda/Toyota. All makes have one-off issues, I think. Porsche is as good or better than most is my conclusion. I replaced my MDX with (egads!) a Cayenne which will likely blow a transfer case. I sleep okay at night :-)

cheers!

hmmm I just had my oil changed with what I believe is mobil 0W-40 last week, but this has me interested to find an independent mechanic to swap in the Motul. Will research more on it, thx

Just change it yourself, it takes about 30 minutes.

would love to. unfortunately rent in LA where my car is in an underground parking garage and I think I own a screwdriver and drill, that's it

There’s a video of a guy in an apartment building garage working on his 991..changes the oil, pulls off the bumper, changes air filters...tools are cheaper than dealer/Indy labor after you use them twice.

there's also a video of a guy stuffing a 4 foot sword down his mouth I don't know what your point is. there will be a time God willing where I can have a garage/space to enjoy taking the time to learn more about the engineering & components of the car, but for now I'll just utilize an indy or dealer

Lol you got me with that one lol

lmao :cheers:

Isn’t start up where most wear can happen? Isn’t 0-40 better for that? I am running 0-40 mobile 1. Soooo, Motul is a better option? What weight should I run?

Motul
 

Im interested as well. For warranty is motul Porsche approved?

Far and few between still. The reason I believe we don't see as many failed 9A1 blocks is that cheap factory crate engines were available up until sometime last year (at least for Caymans) and shortblocks are still very inexpensive, making the dealership still an attractive option compared to rebuilding the engine yourself.

The first one we fixed was in 2011 - a 2009 C4S from Kuwait:

https://cimg9.ibsrv.net/gimg/rennlis...c3840b4a87.jpg
https://cimg1.ibsrv.net/gimg/rennlis...ddfac4bdc8.jpg
https://cimg2.ibsrv.net/gimg/rennlis...bf267b1a7d.jpg

Sorry I don't have better pics - these were the ones the customer sent me years ago.

Motul 8100 X-Cess 5w40 is still a factory approved A40 oil that is full SAPS.

I will never understand why Mobil 1 is constantly bashed and blamed at least partially for many of these Porsche engine maladies yet Porsche continues to use it as factory fill and has done so for over 20 years.

If it was truly as inferior as some believe then Porsche wouldn’t be using it period.

Mobil 1 is great for fuel economy and horsepower. It's hard to find an oil that will beat it in those two areas. That's two reasons why.

So this is the best option, ok I gues I will try it at the next change.

Motul 8100 X-Cess 5w40

Many over on the Cayenne forums swear by Liqui-Moly and their Ceratec additive.

dont idle car, especially when cold and extra fuel is injected. Start car and start driving with low rpm

I use this oil:


https://www.fcpeuro.com/products/por...kit-ox254d4eco

Can you please tell us about the new Driven Brands DI 40 Oil .

Thanks, Cman21

I'll explain the main differences between DT40 and DI40. DI40 has a bit higher HTHS to help fight fuel dilution even though it's a 0w40 rather than the 5w40 of the DT40. It has similar levels of ZDDP making them full SAPS oils, however the detergent package is completely different between the two. DI40 has significantly less Ca detergent, as Ca and Na both contribute to LSPI.

I liken the difference to the A40 M1 and C40 M1. The C40 is formulated to prevent LSPI and also has a higher HTHS viscosity, however that's where the similarity ends, as the C40 is designed as an emissions protection formula and by that token, can't be full SAPS.

The label recommending Mobil-1 is not based on oil performance but how much the Exxon advertising department pays to have Porsche and other manufacturers put the label on their cars. Some owners believe Mobil-1 is the sacred cow of oils and use it despite there being a long list of Porsche approved oils by other manufacturers. Replaced engines under warranty is chump change compared to what Porsche gets paid by Exxon.

I am going to do the exact same thing. I found Motule oil on Amazon which I ordered.
My car is 2013 Carrera S. I just changed oil last week.

^^This. It's all about the $$$, not the performance. Mobil 1 has gone downhill, go back 10-12 years, they used better base stocks. Now it's just garbage. Castrol is superior to Mobil 1 these days.

And this is exactly the point I was trying to make. This is also exactly how a forum wildfire begins..... "WARNING, DRAIN THE GARBAGE MOBIL 1 FROM YOUR 991 OR ELSE!!!!"

One could just as easily say that Motul, Driven , Liqui Moly etc. etc. have their own marketing agenda and campaign to dethrone Mobil 1 in order to make room for their products in a somewhat cornered market.

Porsche has placed it's reputation on Mobil 1 for decades and it's insane to think for a second that they would risk that for the sake of some kick back. As far as I know there is ZERO evidence that Mobil 1 is causing any early or abnormal engine wear in street driven vehicles and the speculation otherwise should be looked at with far greater scrutiny.

Yeah, these threads always remind me of the sketch with the Chewlies Gum salesman in Clerks.

The reality is that if Porsche is selling us out to ExxonMobil, then it is going to be one of a hundred similar compromises that we don't have any control at all over. It's probably like the tires. Sure, we get Pirellis when most of us would prefer Michelins because they make a tiny margin of difference in magazine tests at some cost in everyday driving qualities. But that doesn't mean the Pirellis are actually bad tires, or in any way inappropriate for our cars. If they were, then Porsche could generally be trusted not to make such a decision on our behalf.

Warm up your car before hammering on the gas pedal. Insist that others such as dealership lot porters do the same. Don't buy used cars from people you don't trust. Then it will be fine. Usually.

The critical piece of information is that Mobil 1 is empirically (keyword empirically) inferior in every single oil performance metric. Mobil 1 was good stuff until circa 2002 when Exxon bought them out and dumbed down the ingredients.

https://www.6speedonline.com/forums/...engines-2.html

Mobil is probably the reason for exacerbating excessive wear on the cam lobes in the early GT3 motors too. Mobil 1 was an excellent oil until Exxon bought them out. The 4-ball wear test results posted previously are horrible with Mobil 1, reason alone to switch to another brand.

That's hilarious because I don't recall Porsche making a single mention of oil quality being a factor with the 991.1 GT3 finger follower issue which was traced to a metallurgical defect in a few small batches of engines. What's even more hilarious is the fact that Porsche then extended the warranty on those engines to 10 years or 120,000 miles while continuing to recommend that very same oil you believe caused this issue in the first place! :roflmao:

What....anybody can post anything on the internet and it doesn't have to be fact based? Shocking. ;-)

I recall accusations against M1 in the mid 1990s regarding camshaft failures on engines that used non-hydraulic lifters. Mostly Asian motor designs IIRC. Affected cars ran on the race track. Don’t believe they ever proved it was M1.

Part of the G-Engine "fix" to mitigate the excessive cam follower wear was improved OILING (keyword oil), you know, that fluid that mitigates metal to metal wear.... Look at the Mobil 1 ASTM numbers between pre Exxon and post Exxon. BIG change in performance, more specifically HTHS, and viscosity @ 100 degree C. Mobil 1 no longer maintains a good oil barrier at high temps, it also has a much higher sulfated ash weight. All these things exacerbate metal-metal wear in high stress high temp environments.

Porsche is in bed with Exxon/Mobil 1 financially, they would never point the finger, especially when oil is a FACTOR not the mechanism. It's very important to make that distinction. Also, Mobil 1 has excellent Racing oils and their European blends use superior base stocks, so it's also apples to oranges with respect to North America, which get's screwed with our Mobil 1 0W-40 "European Formula". I would never put that junk in my 9A1 again. Especially after the positive empirical evidence I have personally witnessed.

But hey, drop that Wal-Mart $3 a liter oil in your six figure 911, it's a free country after all.

Hmmm ok I am just about sold lol

Out of warranty now anyways so I might as well now exercise the freedom of choice, will look into getting Motul 5W40 Xcess 8100 put into my 991.1. If it could mean more healthy engine I'm all for it

Edited just for you: That's hilarious because I don't recall Porsche making a single mention of oil quality being a factor with the 991.1 GT3 finger follower issue which was traced to a metallurgical defect in a few small batches of engines. What's even more hilarious is the fact that Porsche then extended the warranty on those engines to 10 years or 120,000 miles while continuing to recommend that very same oil you believe caused this issue in the first place! https://rennlist.com/forums/graemlins/roflmao.gif

There seems to be a lot of confusion between lack of lubrication and oil quality along with a lot of speculation yet no supportive evidence to your claims. Until you can provide data from a top engine lubrication engineer along with an engine designer that can clearly show a connection between GT3 engine issues, this supposed 9A1 bore scoring issue and Mobil 1 0W-40 I would suggest cooling off with the absurd exaggeration and fear mongering until an actual expert or Porsche itself gives you reason to believe otherwise. Rennlist deserves better.

Nice discussion. I should not have been so reactionary. What made me believe that mobile 1 performed poorly was that graph that was posted. It showed M1 to have the most metal wear on the test. Who knows if that is significant.
Anyway I am sticking with M1 for now and might try Motule oil this winter at my next oil change.

Thanks for all the info and opinions on both sides of the issue.

"OILING" refers to availability of a sufficient quantity of oil in the appropriate places, not the brand or additive package.

It seems that this issue shows up in just one cylinder, so perhaps the problem is not so much which brand of oil is in use, but whether the injector is at fault due to leakage, has a misdirected spray pattern, or is governed by an incorrect cold start duty cycle.

I ran Mobil 1 full synthetic 5w-50 oil in my '15 991.1 GTS, starting with the first oil and filter change at about 1,000 miles. After that I used a baseline of 5,000 mile intervals, except that I did additional changes after each four track days during a DE season. The car was in warranty so I wanted to use a Porsche-approved oil. At the time (don't know now) the only approved 5w-50 was Mobil 1. Excellent oil analysis on every sample. I never had to add any oil in the three years I had this car. Being very careful with loading the throttle until the oil is fully up to operating temperature always seems to be a requirement for engine longevity

I've also had excellent results with Liqui-Moly and Motul products, but have no experience with either in a 9A1 or 9A2 motor. I'm planning to try Amsoil this year in both my 69k mile '96 993 C2 and 77k mile '02 986S track car.

They added additional oil-channels so more oil could flow on the cam lobes that were exhibiting excessive wear. Excessive wear is also mitigated by a better oil. Mobil 1 is an inferior oil, with inferior additives to mitigate wear. It scores poorly in all the ASTM performance metrics. All these FACTORS contribute to bore scoring and the like. This is not a one-dimensional problem, it's combinatorial.

Without oil analysis, the only thing you can say about any oil is that the engine runs and hasn't has a catastrophic failure. With analysis, then you can grade the lubricant's performance A, B, C, or D.

Oil analysis is hit or miss. People put too much stock into a murky science at best. Go ask the E9x/S65 owners how effective their Blackstone Oil Analysis worked for them when many of them won their rod-bearing lottery shortly after a "successful" Blackstone analysis....

Empirical performance data is the most useful data. Mobil 1 has poor ASTM empirical performance data. This isn't a difficult concept.

Seems like weight has a hand in this? PAG recommends 0W40 but seems like many are running 5W40. Due to cold weather and/or cold start? Didn't know people ran 5W40 in LA but some do

Yes. 5 vs 0 provides better protection when hot. 0 is all about manufacturers hitting their MPG numbers. Lower viscosity, lower wear protection, better gas mileage.

Interesting, thank you for bringing that up. I assumed Mobil1 was still the same old good oil, wasn't aware of a decline in formulation.
It's not a religious issue to me, if Motul is provably better (and the above posting seem to indicate so) then I'll use motul. I just ordered some.

Ok lol yet another reason to switch, thanks bro. Auf wiedersehen m1 0W40

Used oil analysis is only as good as the lab that is used. Blackstone's unit averages and commentary lead people to believe their engines are ok when in fact, they aren't.

Isn't this test posted earlier generally known to be a bull$h1t test for car engines???



https://secure25.securewebsession.co...ball_large.gif

No. The test is an actual ASTM test, likely carried out by SWRI, who Driven and even OEMS use for similar testing.

Perhaps you are thinking of a Timken Falex tester, which the results can be easily skewed depending on how the load is applied, but mostly by how much moly is present in the lubricant.

I agree, some labs are better than others. But oil analysis (spectroscopy) is still a inconsistent/murky method/science wrt oil. Especially with the varying quantity of additives high-end oils use, which further obfuscate the results.

These are some of the links that made me question it.....

https://www.bobistheoilguy.com/forum...Number=1584948
https://forums.noria.com/topic/4-bal...lick-marketing
https://www.eng-tips.com/viewthread.cfm?qid=38168

Brinelling is brinelling.

Even the best oil won't do a good job if it doesn't reach the surfaces that need lubrication. Now that Porsche has made the necessary engineering changes, we might find that a GT3 engine with Mobil 1 fails in 221,144 miles while one with your oil of choice makes it all the way to 223,930 miles. Conversely, an unmodified engine might frag itself in less than 50K miles through no fault of the oil.

In other words, nothing in the history of this particular problem tells us anything about the effect of oil/additive quality. Agree/disagree?

Oil Analysis is essentially "Tribology" which is a branch of quite many scientific fields such as Chemistry, Engineering, and Physics. Tribology is a highly disciplined quantitative research science. Oil analysis is not spectroscopy. Tribologists use spectrometers and FTIR. Maybe that's what you're thinking?

Why is this graph considered relevant to Mobil 1 0W-40?

I suggest you read this: https://www.blackstone-labs.com/abou...-oil-analysis/

"Spectral exam:
In the spectral exam, we take a portion of your oil sample and run it through a machine called a spectrometer. The spectrometer analyzes the oil and tells us the levels of the various metals and additives that are present in the oil. This gives us a gauge of how your engine is wearing. To learn more about the elements we look at and where they come from in your oil, go to our Report Explanation page."

Wow. I can't believe I stumbled upon this thread. I thought it was just us M96/M97 owners that had this bore scoring problem.

Spectrometry, and spectroscopy are similar but different (apparently). Spectrometry is what I meant.

Hahaha... You're funny! Did you not read through my reply?

This says nothing about the academic field of science that deals with lubrication. This just proves more of my point that "oil anaylsis" is NOT spectroscopy. That's like saying a Biochemical Analysis is a electrophoresis.

You're getting tangled in your web Airbag.

Oil Analysis comes out of the field of science called "Triobology"! Tribologists use Spectrometers or Spectroscopes. It's an instrument NOT a field of science!

Oil analysis is Spectrometry, using a spectrometer. Semantics wrt spectroscopy vs spectrometry IMO.

From wikipedia

"Spectroscopy and spectrography are terms used to refer to the measurement of radiation intensity as a function of wavelength and are often used to describe experimental spectroscopic methods. Spectral measurement devices are referred to as spectrometers, spectrophotometers, spectrographs or spectral analyzers."

Tribology, is NOT oil analysis, not in the context of this discussion. It is the study of friction, wear, lubrication, and the design of bearings; the science of interacting surfaces in relative motion, but thanks for playing "Professor"...

Airbag - don't flush all hope down the toilet for youself. I know you're scrambling around with Google and Wikipedia at the moment to try to cover your tracks and not look so stupid.

Please stop the madness! Get off the internet and go pick up a normal phone. Call ALS global and find someone that is willing to explain the science of Tribology to you and how it relates to oil industry.

That's a great point! The average person is not going to know all the quantitative measurements contained within the UOA; therefore, they rely heavily on the commentary to make future judgement calls about their engine. If the commentary is too broad and doesn't apply specifically to the engine, then it's a good chance the problem will be ignored.

"Tribology includes the study and application of the principles of friction, lubrication and wear."

You're the very definition of simple-minded. If the cylinder is scoring the only way to determine would be from spectrometry (which is a field of science professor) to determine the content of materials/metals in the oil. This is a STATIC test of the oil, and since RELATIVE MOTION does not apply, neither does Tribology. Viscosity test, yes, tribology applies, but not bore scoring and spectrometry.

Ah, this is better. I know Wikipedia is your current lil' friend, but let's take this a little farther shall we?

Repeat after me...

Oil Anaylsis is not Spectroscopy. (repeat)

Oil Anaylsis is not Spectrometry (repeat)

Oil Anaylsis is not Spectrometer (repeat)

Oil Anaylsis is not Screwdriver (repeat)

Oil Anaylsis is not Kermit the frog (repeat)

Oil Anaylsis is not unicorn (repeat)

An Oil Analysis is a study that comes from the science of Tribology. (repeat)

Yay!!! You got it now!

Only one person post about cylinder scoring and the rest is about expert opinion on oil lubrications. The 996/997 crowd must be laughing at us

(face palm) Why do I bother?

Airbag, listen. Stop trying to save your ship. Let it sink.

You made a bold statement that "Oil Analysis is Spectroscope". Then you said, "Spectrometry is what I meant"... Therefore, you were basically saying that an "Oil Analysis is Spectrometry".

Now, are you saying spectrometry is an unique academic field of science within itself?

What really is your story??? It keeps changing. Please enlighten us!

I admire your passion, but you're losing the context of the discussion in semantics. My story never changed. Spectrometry is a field of science (wikipedia told me so). Only way to determine if material of the cylinder (bore scoring) is in the oil is with a spectrometer, which is the sole portion of the oil analysis report that has forever been in the context of this discussion. Tribology is very macroscopic definition, with little relevance to very the detailed context of this discussion IMO.

When I stated "Oil analysis is spectrometry" I meant "Oil analysis includes spectrometry".

I have to go now. My mommy needs to use the internet, so I have to get off of Wikipedia so I can go chew on tin foil and play with my Velcro shoes. Thanks for the enlightening discourse Nutty, your exemplary knowledge is an inspiration to us all.

Look Airbag. I'm here to help you.

You're now making knee jerk reactions because you don't want to look or be wrong. You keep saying something different and now you want to blame it on "semantics". Semantics have no application here, but only prove you're grasping at straws. Now you want to make me think "your story never changed"? Really?

All I tried to do is simply correct your original statement "Oil Analysis is Spectroscopy". That's like saying "Carpentry is hammer" or "Astronomy is Telescope". lol :nono:

Again, an Oil Analysis (especially as it applies on this topic) is a study that comes from the science of Tribology. :thumbup:

You think somehow I've lost the core discussion of bore scoring? :nono: I've been following bore scoring for many years and how it has plagued the M96/M97. Now I notice the 9A1 is wanting to join the party. Yay! Plenty of room for more!

Listen, this thread was moving just fine until you made a blanket statement that "Oil is Spectroscopy" and is "murky" science. Then you say, "oh I meant Oil Analysis is Spectrometry" ... And, then you tried to convince me that Spectrometry is a field of science within itself. :icon501: And finally, you're saying that you REALLY meant... "Oil Analysis includes Spectrometry". (face palm) :confused:

When all else fails, you blame it on semantics. :banghead:

But nothing changed, right?

Ok, got it. Thanks.

Back to the original topic...I hope this issue does not occur to many of us.

Oil analysis carried out by labs like Blackstone is done to look for contamination and foreign elements. They couldn't care less about the oil itself, it's not their job. What Blackstone does is as different from what tribologists do as what your mechanic does is different from what an automotive engineer does.

This entire thread is bad, and everyone participating in it except me should feel bad.

LOL

hahaha funny line!

Seriously, please expound on the difference between Tribologists and Blackstone?

:roflmao: speak for yourself, I learned a lot in this thread. Mainly that Porsche doesn't know anything about engine oil.

I agree.

That doesn't surprise me. :rolleyes:


I'm a sucker for a good analogy. Please show us your power Noah... flood us with information... split the waters of knowledge man!!

Basically, your analogy is this...
"Blackstone is to a Tribologist like a Mechanic is to an Automotive Engineer"

Expound for us. Are you saying that Blackstone Lab techs are basically kids with home science kits?
:roflmao:

I have a 996.1 3.4L and it loves Liqui-Moly Molygen. Noticeably smoother idle and revs like a sewing machine at high rpms. I have a Ferrari California and it absolutely hates Liqui-Moly. Liqui Moly Leichtlauf made it idle like it had a broken engine mount and it would shake the entire car until I took it out. Any changes in idle is extremely noticeable in a flat-plane crank, front-engined V8 (probably why they never used it until the F149). I used Ceratec in my SAAB turbo. Awesome product. Silkened up a high-mileage engine.

Getting back on track, I went back and re read the " bore score and seven years ago" article from the Feb 2019 issue of Panorama.

Other than outlining the entire situation and awesome rebuild work utilizing LN's incredible fix, there is no mention of what might have caused the issue to occur in the first place. The authors car ( Carl Spencer) had extremely low mileage at the time on what appeared to be a well kept 997.

SO the question is : What is the leading theory among experts right now as to the cause of this bore scoring issue? Why has it become the most prevalent issue now seen by Charles Navaro at LN?

More importantly and most concerning is how does what happened in the M96/97 engines cross over to the 9A1 used in the 997.2 and our 991.1's? Other than the engine configuration and basic layout, the engines are completely different right down to the cylinder liners.

Check out Jake Raby's most recent videos on Bore Scoring on the Rennvision YouTube Channel. It's also shown on Amazon Prime. I suggest watching at least part 1 and part 2 in order to answer your question(s).

Rennlist always delivers - this thread turned out to be quite an unexpected treat!

Any other theories on what is most likely to have contributed to scoring in just one of the six cylinders?

Injector failure leading to pre-ignition (Some people call it LSPI, I disagree, just plain old pre-ignition, not enough BMEP to hit LSPI in a non forced induction motor)

I contacted Jake Raby’s team about 991 bore scoring, see the below response:

Thank you for your email about cylinder scoring.

Although most emails about cylinder scoring are from concerned M96/M97 owners with Porsche Boxster, Cayman, and 911 models from 1997-2008, this issue is not one limited just to these models. It can also affect other models with Lokasil or Alusil bores including Panamera and Cayenne models as well as other European makes with similar block technologies. 2009 and later sports car models with the MA1 (9A1) engine can also suffer from cylinder scoring, but it is nowhere near as prevalent as with other models.

In a Lokasil or Alusil bore engine, when the Ferrostan coating on the piston skirt wears through or flakes off, the result is aluminum to aluminum contact in the cylinder bore which causes adhesive wear, also referred to cylinder scoring.

Based on over a decade of observations, bore scoring is typically limited to models with forged pistons, so the Boxster 2.5, 2.7, and 3.2 models as well as the Base 2.7 Cayman engine typically do not suffer cylinder scoring.

Engines with failing or bad injectors or anything that might contribute to the engine running too rich can also cause cylinder washdown, leading to cylinder damage, but this can occur with any engine or cylinder technology, however the Nikasil process used in earlier aircooled Porsche engines is one of the most durable cylinder finishes and not prone to scoring.

Watch for one tail pipe being sootier than the other or for ticking noises coming from the engine when at full operating temperature. Misfires with fouled spark plugs coupled with increases in oil consumption aren't always the first signs of cylinder scoring.

Here are a few things you can do to help lessen your chances of scoring:


1. Change your oil every 6 months or 5,000 miles with Driven DT40 on 1997-2008 models with the m96 or m97 engine and DI40 on 2009 and later models with the MA1 (9A1) engine. If you do frequent, short drives or operate the car in a cold climate, you should change your oil every 3k miles or 3 months.


2. Use Top Tier fuels and Driven Injector Defender at least every 3,000 miles or better every fill up.


3. Install a low temperature thermostat.


4. Especially in colder climates, once the engine gets off cold start, don’t idle the engine any more and start driving. Limit yourself to 50% throttle and keep the engine under 3,500 rpm until the engine is at full temperature.


5. Add used oil analysis to your toolbox. Scored cylinders typically will be visible in test results with elevated aluminum and silicon levels, often with reduced oil viscosity and increased fuel contamination.

6. Interrogate the DME to observe fuel trim values and check for pending or active faults regularly. Beyond malfunctioning mass airflow (MAF) or oxygen (O2) sensors, changes to fuel trim leading to rich operation are indicative of a problem that can also stem from vacuum leaks from cracked AOS vent tubes or oil fill tubes.

Lots of great information, Thank you for sharing!

It appears to me after watching the Flat 6 videos that the primary source of this issue regarding the m96/97 engines lies in the inherent design and manufacturing processes that are exposing a weak point in much the same way as the IMS issue where by under less than perfect conditions excessive wear/damage can occur.

For instance, I did not know that those m96/97 engines had a slightly less than favorable rod ratio resulting in additional side loading of the piston skirt against the cylinder wall but that seems to be one of the bigger contributing factors in this along with the less than optimal durability of the lokasil/alusil coating. I understand there are many other factors in this "equation" but I'm trying to find the similarities between the m96/97 engines and the 9A1.

Does anyone know what the rod ratio is in the first gen 3.6, 3.8 (997.2) and the second gen 3.4 , 3.6 ( 991.1) 9A1 engines?

Add Item 7.

7. Never drive a Porsche that is not under warranty

Seriously, I have a Ph.D in aerospace/mechanical engineering, am a veteran of the aerospace industry, and have taught mechanical design courses to engineering students for many years. A street vehicle that requires steps 1 through 6 to avoid catastrophic engine failure in normal daily use represents a badly flawed design. The only way I can rationalize my continuing use of a 991 as a DD is by maintaining warranty coverage while exerting only a reasonable level of care and maintenance. Using Top Tier Fuel and avoiding flogging a cold engine, for example, seem like good general practice with any vehicle.

I’ll gladly buy your fully depreciated vehicle when you are done with it...depreciation costs will trump non-maintenance related repair costs 9/10 times.

Send me a PM in 7 years when the planned extended Fidelity Platinum warranty on my 2017 991.2S is about to expire and you may have a deal. It's not the maintenance cost that I want to avoid, it's the hassle. My days of playing mechanic, or even indirectly dealing with involved maintenance details, are long over.

Deal!

Sounds good.

If I decide to move on to a later 991 before seven years, I will give you a chance by PM to buy my depreciated, low-mileage, never abused, maintained to factory specs, but no more, 2017 MT S.

I will be here!

That's good advice for people that can afford it, but we must also realize that there a lot of people that would love to experience a Porsche in spite of the lack of a warranty. I would argue that most of the 986, 987, 996, and 997 crowd in the forums probably bought their cars used without any type of warranty. That's why they come to the forums - to learn how to repair and service these wonderful machines themselves. It's unfortunate, these machines come with so much unforeseen issues that can make a childhood dream turn into your worst nightmare.

My advice is buy what you can afford and know exactly the cost of ownership before you sign on the dotted line. Never go into buying a 911 blindly.

I feel like this entire thread is making a mountain out of a mole hill. Bore Scoring as of now is not a major issue on the 991 generation 9A1, and all this speculation is just that, speculation.

This seems obvious, aerospace guys have an extremely low tolerance to risk. Option 7 is rather unrealistic for most people though, and personally not a big deal. Don't buy what you can't afford to fix. My 991.1 is not under warranty, and I prefer it that way, I don't need to worry about the modifications I'm doing to the car killing my warranty.

Haven't seen a lot of 991.1 engine rebuild or heavy maintenance Indy's yet. What would this mean for an out of warranty owner in actual dollars? If it's just a bucket could that be replaced? How much?

Assuming 22K miles and zero consumption at that point, what's the likely hood of suddenly developing something like that?

Exactly, you won't find an engine out there that doesn't have some examples with bore scoring. This is the first 991.1 I've heard of with it.

What was the cost saving or benefit of using Alusil instead of Nikasil?

According to Jake Raby, they switched due to environmental regulations on the manufacturing of Nikasil.

FYI, deep in the last century, when discussion turned to Porsche and Alusil, it was in the context of the entire cylinder block cast in Alusil.

Nikasil and Lokasil are cylinder wall coating processes that enable the cylinder block to be cast from normal aluminum (where ‘normal’ means ‘cheapest-possible.’)

Nice. Same reason why modern car paint is garbage, I hear.

I just had Motul 5W40 xcess8100 put in my 14 50th and I am sure it is 100% psychological but the car felt slightly snappier driving home

How often do you guys change oil? 5k miles? 10k or 1 year? I am sure this is like break in with different answers

5k miles or one year, whichever comes first

that was my line of thinking as well 👍 thanks

5k or 6 months whichever comes first for me.

I am going to start following the advice from that expert in GA and do every six months. Until this year, my car was still under CPO and being serviced by dealer. It is not that extra expense to do semi-annual. I think I am also going to switch to Motul 8100 x-cess 5w40 (dealership was using Mobil1). Regarding the other advice, I have been using Shell premium since I got the car

Any reason not to use Motul 5W40 X-Cess 8100 in the 1.2 cars?

Funny you should say that. I saved all of my lottery money and got the bearings done a week ago, also the plugs and motor mounts, 27,632 miles and the wear is unacceptable.

So now I'm reading this depressing thread...
I don't track nor drive in the winter but most trips are regrettably short.
So I'm fine with more frequent oil changes.
Is the consensus to go with 3months/3k miles or 6months/6k miles?

Are these the original spark plugs? Why are they so "black"? Is the erosion natural and reasonable or is there a bore score detected?

These threads teach a lot but it is frustrating to read that there is no reliable engine.

I'm considering switching to 997.2 or 991.1 and all that stuff gets the craving... :( Can only Metzger sleep soundly? Thoughts ..

Given the thread’s earlier reference to E9x owners and the fact that there are 8 plugs and rod bearings (from a V8 I assume) I’d say that’s from his E9x M3 and not a 9A1 therefore no bore score likely involved :)

Oh goodness... to quote Heath Ledger as The Joker- "And here, we, go!"

Having had a 2003 996 on original IMS/RMS for almost 30 months, and neither of my top-tier techs in the Houston area never once replacing such bearing for fault, or otherwise in their combined experience, I can tell from firsthand experience how overblown that whole deal is. But if you can't see sleep at night without it, there are cheap options to 'fix' it, until you have to 'fix' it again, depending on who sells it to you... Even asked my local PCA chapter and again, not once has anyone experienced this issue, so who knows. Not saying it doesn't happen, but, it certainly is overhyped from real-world involvement with owners who also TAKE CARE of their vehicles... many 996s/997.1s were dailys and rode hard and put away wet and it shows in the classifieds for many cars.

I see people talking about Honda/Toyota/etc. 'quality' in this thread, which having supposedly the 'most reliable car' in the world in a Lexus RX350, I can certainly attest that even with the internal functions, like the damn door locks, my has Lexus failed much more than my 2003 C4S. I mean really- Denso/Toyota can't make door locks that can't last for more than 6 years?? Crazy. And it's not like Lexus service is really any more affordable than Porsche when it comes to parts like that.

Bore scoring issue is resolved in the 9A2? I believe aka the 991.2

991.1 scored cylinder #4
 

My 2013 911 991.1 has 16000 kilometers (9000 miles) still original tires and brakes but just discovered at least 1 badly scored cylinders. I am in contact with Porsche to see if they will help given the car has never been tracked and driven normally.

what prompted the cylinder inspection?

I just noticed this noise from the right side of the engine on my 2013 C4S today. Sounds a little different to me than some of the bore scoring videos I’ve seen. Anyone have thoughts?

That engine sounds normal to me. Can you be more specific in describing the noise that concerns you?

Just saw this quote and as an aerospace engineer myself this is completely unrealistic and frankly insane advice. Risk management requires an evaluation of both the likelihood and consequence, not just fretting about worst-case scenarios. Yes the consequence may be high but by virtually all accounts the likelihood of bore scoring on a 9A1 or 9A2 is very low (probably much less than 1% to date). If you can get an extended warranty for 1% the cost of an engine rebuild then this advice might make sense. But you can't, it will cost you as much as 20% the rebuild cost for 5 years of coverage. This makes zero financial sense and is the reason that engineers usually aren't in charge of risk management. To us anything higher than zero risk is unacceptable, but that is not how the world works, sometimes things blow up. The vast majority of folks would be far better off self-insuring against this extremely unlikely event.

Completely agree with the mitigation steps (frequent oil changes, don't lug, easy does it until the oil is warmed up, etc.) as these have a very low cost and no downside (unless you pay for $500 dealer oil changes which is a whole different issue).

I’ve decided to stop worrying and learn to love the bomb. If the engine blows I’ll send it off to Flat 6 or Guntherwerks or some shop like that to rebuild, bore/stroke out to 4L, up redline to 8,000+ rpm and see if individual throttle bodies can be added and it will still be cheaper and more comfortable than a GT3 plus have useable backseats. I don’t need the suspension/chassis upgrades to match GT3; I already feel as though the Earth has tilted on its axis every time I take a corner on the track hanging on for dear life.

If it doesn’t blow then I’ll buy a used GT3 and start saving for a Speedster and those glorious ITB’s it already has.

Dream big people and worry less. We drive awesome cars.

Well, I’m now on my third 991.1 engine. First engine got horrible bore scoring at 16k miles. Replacement engine got scoring only 2k miles later.

The first replacement (2nd engine) they only replaced it with a short block so I suspect faulty fuel injectors were causing the wear since they just transfer those over.

now I have to decide if I should just sell the car or pony up for a fidelity platinum warranty and risk it. Thoughts?

You last statement is confusing to me. What risk would you be taking with a Fidelity Plat plan if you decide to keep it.

As for you running into 3rd Bore scoring issue on same car, the chances of that are minimal, if not zero. If it does happen, you have to ask what other factor is part of this equation (operator error). Not blaming you for any of this, just mathematically, you have to start eliminating factors.
I would keep the car as you know this car and it now has a new engine.

We had a crate 3.4 987.2 engine score bores in a race car in less than 10 hours. Had a faulty injector. Likewise, we've seen instances where a shop used a factory shortblock on a 997.1 and keep the same injectors - engine scored the same cylinder bore again only 3,000 miles later. Injectors were tested after the failure and found to be bad. It's bad enough we made injector replacement required on rebuilds in the directives we provide customers.

Out of curiosity, do you know if it was the same bore that scored the second time?

Yep, same exact bores were scored on the second engine (3 and 4). They didn't replace the injectors the first time around so it sounds like that's what happened. On this latest engine I implored them to replace all the injectors and also change airflow sensors just in case (since it sounds like the typical failure mode is either leaky injectors or the mixture being somehow way too rich). This does give me some peace of mind though that I didn't just get super unlucky. Likely the injectors were the culprit then.

Charles, can you describe the linkage between a bad injector and bore scoring?

One of the ways they can fail is that a bad injector won't atomize the fuel properly and ends up washing the cylinder bore down. As fuel isn't a lubricant, lack of proper lubrication ends up killing the cylinder bore. They can also leak, flooding the cylinder with fuel when then too washes away the lubricant.

We see this happen with engines with nikasil bores as well, however it's the piston rings that get wiped out in that scenario.

Since it was the same cylinders I would agree that the injectors were the likely culprit for the second failure. Very good thing you got them to put new ones in the last time around.

What are your thoughts on BG 44K fuel injector cleaner? Supposedly it is the best of the injector cleaners.

Possible preventative maintenance?

I use a bottle of Driven Injector Defender + Booster every other tank of gas. But then again, in my area, there are no easily accessible top tier gas stations nor are there ethanol free fuels. If you have top tier fuels, I'd probably say you are safe to use a bottle every 3,000-5,000 miles (I'd say at least every 6 months).

What is critical is that whatever fuel system cleaner you use has the additive Polyether Amine (PEA). That's the strongest cleaning agent you can buy.

Also if it takes you more than a month to go through a tank of fuel, you really need to use some sort of additive to stabilize the fuel unless you have access to ethanol free fuel like REC90. Bad fuel kills injectors.

Are you referring to this?

Yup, that's what I use. We also sell it as well.

https://lnengineering.com/products/j...tle-70056.html

There is also a version without octane booster, but there is no price difference, so why not have the octane booster. I know in my GTI and Mercedes I see a noticeable increase in fuel economy on my regular route (60 miles each way from home to the shop), but both are turbo charged, so the extra octane is probably why I see that improvement. Even more so in the winter when stations have winter blends which are much crappier than summer blends.

Charles, in these instances of faulty injectors that you've seen were there any tell tale warnings in the form of rough running and or an engine malfunction light due to a misfire or overly rich mixture?

I don't know what the limits are for adaptation on the later cars, but on an M96 or M97 it can add or subtract 20% I believe before it will throw a CEL. What ends up happening is that the ECU starts adding more fuel to compensate which makes the problem worse.

Interesting. Thanks. All I see is 928 engines and bore scoring is pretty rare - and even-more-rarely catastrophic - even with serious wall washing. One might suspect that the Lokasil process just doesn't work nearly as well as the last-century cast Alusil cylinder blocks.

So sorry to hear of your troubles. Did you have a CPO warranty or did Porsche cover the repair as an exception/goodwill?

There were significant changes to the Alusil process from when the 928, 944, and 968 engines were originally produced. Specifically the silicon exposure process was changed which can result in more torn of fractured silicon particles which then in turn reduce the load bearing capability of the cylinder walls. Secondly, the iron clad coating on the pistons was replaced with a printed wear pad which has shown itself not to be anywhere as durable as the older plating process which manufacturers went away from because of environmental reasons.

Lokasil suffers from the same issues for similar reasons, but there is a lot more going on there. The fact that Porsche was the only manufacturer to ever use Lokasil and they stopped using it after the M96 engine says it all.

Just curious, Charles, if you have any comments on the performance of the Rotating Single-Wire (RSW) bore lining process used on the 9A2 (991.2) - as compared to the previous processes.

cheers!

Night and day. The RSW or APS coated bores are much more durable. I have experience with Oerlikon's SUMEbore coatings (used in the 918 Spyder among other Porsche and VAG products) and it has worked phenomenally. Performance is on par with Nikasil and likewise has excellent heat transfer like Nikasil since it's only applied .0045" thick. I would not be concerned with cylinder bore scoring on the newest blocks using this technology.

https://cimg1.ibsrv.net/gimg/rennlis...9439ff815a.jpg

Here is a picture of an M96 block we did with SUMEbore after being run and torn down for inspection. Engine was reassembled and is back on the road now. Lake Speed Jr. from Total Seal (previously Driven Racing Oils and Joe Gibbs Racing) owns the car we're doing the over the road testing with. We have done an aircooled Porsche test engine as well and the results were excellent. Our next step is to evaluate some of the other Oerlikon coatings as there are several variants of SUMEbore we'd like to learn more about. Very long term project we are doing in conjunction with Oerlikon, Total Seal, and Flat 6 Innovations.

Wow. Very nice looking work, Charles. Thank you for the prompt reply!

Fascinating technology.....
https://www.sae.org/publications/tec.../2012-01-1992/

Did you apply the thermal coating in Momence or did you have to send the cylinders to Zürich? What is the cost vis-à-vis Nikasil?

Edit: For clarification I am speaking generally about a racing engine where the cylinders can be serviced. I'm guessing this is not the case since for an M96 engine, like you posted, as you would need to ship the entire block abroad.

We don't have the equipment to do it in house ($$$) - we had to send the block out to have it coated. One of my mentors is close friends with the guys at Sunnen and they were kind enough to lend us the tooling to hone the block to the mirror finish required. As you can see, there is zero crosshatch in the bores. There are micropores that hold the oil instead. Neat stuff.

Cost is still prohibitive. It's over four times the cost and that doesn't include the honing.

Yes that plasma vaporization composite technology is so cool. I see how the hone works -- the coating process actually shoot little iron pellets into the cylinder wall creating an uneven finish which, when you come back and hone it out, creates little divots that will hold the oil. Such a fascinating technology......

So, costs aside, compared to Nikasil is this a superior product? It seems like the answer is "probably yes.....but time must be the judge". Obviously it's better ring seal, less oil consumption, etc. Are there any downsides? Are any of the racing teams using this technology? Similar to Nikasil I'm assuming a bad injector can still take out a cylinder?

Thank you as always for the information.

By the way @Charles Navarro do you guys now do rebuilds of the 991.1 engines? I know we're still within the 10 year window where factory short blocks are easily available but in a few years a rebuild may be the most economical way going forward. It would be awesome to get one of these improved coatings on the rebuild and potentially also increase displacement a bit.

We do recondition the blocks and have for many years, however we do not rebuild 9A1 and later engines. Here's a summary of our program:

https://lnengineering.com/products/w...ayman-911.html

With Oerlikon's SUMEbore, there are several types of coating. The one we have the most experience with is their F2071 which is designed for corrosive fuels and environments and actually has ceramic in it. It took some time to figure out the right rings to run and now we're playing with different lubricants. I can tell you it doesn't like Mobil 1 0w40... The F2071 coating is used in Europe for diesel engine blocks where durability and longevity is paramount. There are other coatings that have moly or other materials in the mix that greatly reduce friction and might possibly outperform Nikasil which we are going to be testing with this next round, but I would say the performance is on par with Nikasil, especially from the benefit of heat transfer for aluminum blocks. The big benefit of the SUMEbore process is the environmental benefits over the Nikasil or any other plating process which is considered dirty and all the OEMs are trying to go to environmentally friendly solutions.

SUMEbore has been and is used in Nascar engines and other kinds of racing. Many OEMS have licensed the SUMEbore process.

https://cimg3.ibsrv.net/gimg/rennlis...d81f3cf23f.png


This isn't the most recent list, but is all that I have come across during my time working on this R&D project.

Maybe it is the bore to stroke ratio. When your stroke is relatively fixed since these are boxer engines and the bore gets increased to increase the engine capacity, you end up with more of a side load on the piston and cylinder wall under heavy acceleration than you would with a longer stroke.

Here is a pic. Note the size of the horizontal force arrow.

https://cimg7.ibsrv.net/gimg/rennlis...2c3d8ef047.png

Bore-stroke ratio certainly plays a factor but I don't believe it's as much as a problem on the 9A1 engine as it was on the M96 engines when they increased the stroke to 82mm from the 78mm. The increase in stroke resulted in the piston coming out of the bore 7mm at BDC (versus 2mm on the shorter stroke engines). At BDC changeover, that's putting extra load on the piston skirts and probably contributes to the premature failure of the piston coating. However, there are many factors that contribute to cylinder bore scoring which I spent over a year researching. I wrote a white paper on the topic for those interested:

http://lnengineering.com/files/2019-...er-Systems.pdf

Charles, am I correct in that the GT3, GT3 RS, Turbo and Turbo S use Nikasil whereas the lower 991 (GTS and down) use another process?

The Mezger engines all used Nikasil plated bores whereas the 9A1 based engines have Alusil blocks.

When you say F2071 is designed for corrosive fuels does that mean ethanol specifically or is that a more general statement? I see the blend material for F2071 is oxide ceramics. What if you use no blend material and use an oxide ceramic for the matrix material (F6418)? Looks like friction reduction and wear resistance are off the charts using that coating.

Maybe the most exciting thing is that the cost has apparently come down ~50% in the last 5 years. Given the direction of ICE, definitely seems like this is the way of the future. That is an impressive list of engines.

.

A general statement repeated verbatim from what we were told.

We are taking their lead and evaluating the three primary coatings used by the OEMS (including Porsche). F6418 isn't one of them. Unfortunately I don't have anything more I can share at this time. It's a very long term project.

Agreed. We had approached them years ago and it was impossibly expensive. It's still too expensive for general consumption and the aftermarket, but at least we'll have the first had experience and knowledge of the coatings, processes, and requirements to make it work in our application.

I understand; you've already been more than gracious with what you provided. I know you have been working on this a while because it's mentioned it in your white paper on bore scoring.

Why no rebuilds of 9A1s? Just curious.

I have a 2016 2.7L Cayman, never had any oil consumption issues... although it does drop a bar by the time I'm closer to an oil change. I guess I should start putting in a bottle of the injector defender every 6mo or so, since it's always on top tier gas. Good insurance policy for ~$11. Great thread, thanks.

Thinking about this, so at which part of the cylinder bore does scoring occur at...most of the time?

We have more work than we can handle as is even with only doing bone stock builds. We leave performance builds to our customers we sleeve blocks for.

Typically at BDC, then it works its way up the bore towards the heads. That's why if you scope the bores with the piston parked at BDC you can't see scoring until it's really bad.

There is another component to scoring on 9A1 engines as the piston to cylinder clearance in these engines is very, very tight (.0007" total clearance new) and the bores can move at BDC and close that clearance up to a point that the piston starts to seize.

Sorry to revive a dormant thread but I have been giving this topic some more thought. Could you please articulate what you mean specifically when you said F2071 "doesn't like" M1 0W-40? Thank you in advance, hope all is well.

Could it be that the vast majority of recent Porsche engines run on that?

Whereas if the majority of engines ran on another brand and weight of oil, the same thing might happen?

Right now we are evaluating different oils. We were running a conventional test oil and had no oil consumption whatsoever. When we switched with M1, the engine started to consume oil but it seems to have stabilized at about 1/2 a quart in 3,000 miles. I'm pretty happy with that. I'll add back when we were working with Driven to develop DT40, we learned that different brands of fuels and also winter blends would affect oil consumption. Likewise, some oils seem to be better about oil consumption than others, as does what cylinder material (or coating) the engine uses.

As Porsche did not use the F2071 coating, I can't say one way or not whether the info we've learned during our testing would be directly applicable to Porsche engines with SUMEbore coated bores. We are in the process of evaluating two more different coating used by VWAG (and Porsche) to see how they compare to the coating we have already used in both aircooled and watercooled Porsche engines.

Thank you for the information, I appreciate it. I agree with everything you are saying 110% and you are offering the community good information. Goes without saying but you cannot judge an oil by consumption…..even as a proxy.

Consider the following which is my experience with DI40. At 75k miles my cast iron 2.0T burned basically no oil running VW 502.00 5w-30 but I discovered the timing chain to be severely worn so I could fix things before it completely destroyed the head. In fact using oil consumption alone as a proxy for engine health can be a red herring.

When I switched to DI40, a 0w-40, I noticed increased oil consumption especially right after the switch. It has since stabilized and I now burn about 1/2 - 3/4 quart per 5,000 miles. But the UOA looks solid. I suspect with the thinner 0w-40 oil a little more is making it past the rings. But make no mistake, my engine is extremely healthy. I also noticed I burn a little more during city driving which I think makes sense as the car is idling more and not under load. When I took a 1,000 mile road trip to Chicago a few weeks ago it burned nothing.

In my view a relatively small amount of oil consumption is a small price to pay for running a higher quality oil with all the benefits that come along with it.

Agreed. Oil consumption isn't something necessarily to worry about as long as it's not increasing over time. Some engines will use more oil than others. It's very common for engines with Nikasil bores and the required low tension rings to use a quart in 1000 miles.

Case in point, I have a GTI with the 2.0T with the cast iron block as well that burned a quart every 700 miles and the engine is very healthy with 140,000 miles on it. Doesn't worry me in the slightest.

I can't believe it but had this happen to an acquaintance of mine too. Car purchased at 25k miles (C2s) but hadn't been driven that much for 2 years. 1 month later, clicking sound = bore scoring in two bores after the engine was disassembled. They didn't replace the injectors the first time around. Same issue, and one of the two previously defective cylinders was obviously scored this time. They replaced the injectors this time and things are good. It seems like service centers aren't replacing the injectors by default on the first engine failure. FWIW his car was not CPO and they still covered it (that would've been a very expensive tale otherwise).

I got recommended to use Techron every few months (or at minimum the tank before each subsequent oil change) to keep the injectors clean. Is that something you guys would recommend? The other big thing I've been recommended is an "Italian tuneup" from time to time. And not idling but driving moderately until the engine is well warmed up (because damage is more likely due to the very small clearances right after a cold start). So far (along with my new engine + injectors) I've been fine. We'll see how well this other guy's new engine holds up.

One of the biggest killers of injectors is crap gas so don't use it. Only put the best quality gas in all of your engines -- eg. only Top Tier gas and never get gas at "random" non-brand type gas stations.

Yes, I run a bottle of Techron just before every oil change. I also use the Driven Injector Defender + Booster, which is just as good. As far as "Italian tuneups", yes, these engines prefer to be run at operating temperature and not idled a lot etc, so getting the car out on the highway or whatever pretty often to run it at full operating temperature for an extended period of time, even if you're not banging on it per se, is good form.

I don’t quite understand. The engine monitoring systems on our cars are super sophisticated. To the point where I had a check engine light years ago on an old Boxster simply because there was a little bit of water in the gas and one cylinder had a miss for a few hundreds of a second.. detected! These things record time spent over certain RPMs to a single engine rotation - and yet we’re saying that they are unable to detect a bad injector, twice, which leads to toasting an engine? I don’t get this. I’m not denying it happens or that it was the cause - but it doesn’t compute that the computers are missing this … anyone ?

My guess is the spray pattern is altered somewhat or they become leaky so they're still functional but causing excessive washing of the oil of the cylinders (as has been mentioned on this thread). So it's not like the engine is noticeably misfiring per se (which the computer could easily catch).

Greg, I think n4life’s comment as to why the computer does not flag injector issues is spot on. The computer is looking for misfires or lack of fuel pressure, not altered spray patterns that do not cause misfires. Plus, a leak down issue while engine is off would not be detected because the engine is off so the computer is not collecting data. The best way to monitor injector/fuel dilution issues is with regular and consistent used oil analysis so you can immediately address it should it occur.

Either this is a real problem where all cars are being affected which is not the case, or it is a possible owner issue or a used car purchase where you had no idea how it was previously driven and/or maintained. And if it is not the latter, "fix the damn issue in design and change the process".

We had a guy at work and he would start up his engine in the dead of winter (well below 0F) in the parking lot and race to the street only to have to stop before the oil got to everything. No wonder his relatively new car needed a new engine which Honda replaced under warranty.

Then we have a PCA member who had bore scoring. OK, so the car was bought used, but that was years before the bore scoring started. Of course he bragged that he ran 100% of the power 100% of the time. Yeah right, maybe on the Nardo test track, but you get the idea. Who knows why he experienced bore scoring.

I have another PCA friend who has over 100,000 miles on his 997.1. No issues, but then he is not driving the pi$$ out of it, and certainly not after start up. I personally drive my cars gently for at least 10 miles before taking up the revs.

There is no question this is a real problem. So many variables at play here that it would be hard to distill it down to a simple answer. I have seen engines with very, very low mileage that suffered from bore scoring.

Pound for pound, IMHO a port injected Mezger is still the best technology you can buy for a modern racing engine in this class. It is effectively bulletproof with no true Achilles heel (coolant lines maybe but that's about it). You can bang on that thing all weekend long at a track event and it doesn't even flinch.

Possibly. Per 100,000 vehicles sold, how many engines were replaced within warranty or "good will" and how many were replaced by owners thereafter? Impossible to answer.

Just remembered, another 997 friend of mine had his engine replaced by Porsche shortly after taking ownership of it at the Porsche dealer where he bought it used. He later found out the original owner who had leased the vehicle when he had bought it new had a son who abused it. Personally, I would never buy a leased or rental vehicle.

The only way for your friend to have possibly known would have been to do an invasive PPI before taking delivery and even then it's still not 100%. You can look at over revs and things of that nature but I personally wouldn't even touch a car unless I could get access for a scope into ALL of the cylinders and drop the sump at minimum. Doubt most people or dealers are going to want to do that for a prospective buyer... especially in a market like this which is completely insane. But without doing that as a buyer, you're effectively playing Russian roulette.

In his case, bought from a Porsche dealer and the car was CPO'd.

After reading this thread....991.2 or newer for me!

There's not enough data to even remotely be statistical significant. If you're going to write off an entire generation based on this thread, you're probably gonna write off the 991.2 as well when you encounter the other threads.

Well, see Charles Navarro’s excellent discussion above re: SUMEbore cylinder walls as compared to Alusil and Lokasil technologies. The fuel injectors have changed also….at least in the 992 version of the 92A EVO engine….so Charles’ injector discussion is equally relevant. The tight piston to sleeve clearance that Charles discusses could also be an issue unique to the 991.1. So, pkalhan’s conclusion to prefer a 991.2 engine is not baseless regardless of statistical significance. If it is your 991.1 engine destroyed because of bore scoring (like the numerous examples discussed above by several different members) then the statistical significance to you is 100%.

You can lead a horse to water..............

Except that's now how statistical significance works. With the number of 991.1 cars sold, surely this issue should be more common by now with more conversations around it. Yet this thread is almost four years old with not many owner contribution. Now rod bearings prematurely worn and subframe failure on an E46 M3? IMS bearing issues on the 996? Seems like a lot more owner contributed data there to support significant risk.

Even in the paper Charles Navarro wrote:

Like most performance cars, proper maintenance and car ensures longevity. Performance cars that are driven hard is going to come with some % chance of failure.

And by this accord, I'd have to write off every 996, 997, and 991. Except there are great advice here on preventative maintenance, which I'd argue is good practice for any performance car. Unless you're telling me you can drive a 991.2 and give it full beans without warming it up while ignoring oil maintenance, use cheap fuel etc.

My interpretation of the thread is that poor fuel injector maintenance, poor quality fuel, bad oil, lack of oil change maintenance, not warming up your car... etc can contribute to bore scoring. But are all of those things to be omitted from owning a 991.2 or any other performance car? No.

For what it's worth, I'm not saying that bore scoring isn't real. I'm just saying there I'd like to see more community contributed data to get a better sense of risk. And there is inherent risk with most performance car if not maintained thoughtfully.

I do not disagree with anything you say except your dismissal of pkalhan’s point by discounting the extent to which engineering and material choice (the use of Lokasil, Alumsil, tight piston to sleeve clearances, etc.) contributes to the problem as explained by Mr. Navarro. While proper maintenance and driving (which I frankly assume as a given among the members of this forum) could be a contributing cause, one can avoid the potential engineering defects by getting a 92A engine as pkalhan suggests. It is a reasonable conclusion on his part given the known facts and science discussed above…..even if that statement offends some 991.1 owners …….of which I am a member.

I remember reading something about rod length vs bore.

Good point. I agree. Another potential issue.

Most certainly a contributing factor. With a fixed deck, you typically have to shorten the pin height in the piston and/or shorten the rod, making the rod/stroke ratio less favorable. However I think lack of bank specific pin offsets in the piston are likely a larger contributing factor. Coupled with really tight piston to cylinder clearances and stresses in the castings leading to the bores tightening up at BDC where they meet the main bearing saddles all stack up. Finally add in M1 0w40 which is formulated to the min viscosity permissible for the sake of improved fuel economy along with high fuel dilution and long drain intervals and it's a perfect storm.

Using better oils with shorter drain intervals is the single best thing you can do if you own one of these cars.

Looking to buy one you need to do a PPI including bore scoping and used oil analysis if possible.

That said, like I've said before, the failure rate is much lower for the MA1 engine than its predecessor, but as the cars age, I expect to see more issues. 10 years ago it was mostly IMS bearing failures that was taking out M96 engines and now it's almost 100% bore scoring failures.

So I take it it is not so much a lateral load issue, or?

By the way, on a 991.1 with the 3.8l engine, what is the rod ratio on that engine.

I guess we can agree to disagree. Engineering defects exist with every car. The 991.2 included. It’s not about being offended. It’s about thoughtful risk consideration.

How we choose which cars to own comes down to risk factor.
https://lnengineering.com/products/w...e-scoring.html

His own website notes that proper maintenance prevents bore scoring. And again, there isn’t statistical significance in this thread or any other to conclusive show this is a common problem. At least in my field, that means a large enough sample size.

So it’s reasonable enough for me to conclude that with proper maintenance, the risk isn’t that high until there is further data. And that is unlike other engineering defects in other cars that has a high chance of failure even with proper maintenance and can only be prevented with actual modification.

SUMEbore (or any of the similar thermal spray technologies like transfer wire) is very expensive -- even in mass production. But there is a reason that Porsche moved to it. If bore scoring was "statistically insignificant" on this platform then Porsche could have and would have saved the money and stayed with Alusil cylinders.

Charles' paper never says proper maintenance prevents bore scoring -- it says running a "good" oil (not M1 0W-40 like Porsche recommends) at short OCIs will give you the best odds to. There is more than a large enough sample size, you just don't have access to the data. Very few people in the aftermarket do but Charles would because he rebuilds these engines so can see what comes in the door. He just spelled it out again in his last post above: "That said, like I've said before, the failure rate is much lower for the MA1 engine than its predecessor, but as the cars age, I expect to see more issues. 10 years ago it was mostly IMS bearing failures that was taking out M96 engines and now it's almost 100% bore scoring failures." You can't expect to get any better information than that.

To Charles' point: When I bought my first Porsche 911, a 996, 15+ years ago people "in the know" were dialed into IMS failures........no one really talked about bore scoring. D chunks on the early water cooled engines....not bore scoring. Fast forward to today, boy have things changed......

people seeking out Charles' expertise aren't exactly a random sample of the population, though. so again, we really don't have any "data" and as much as anecdotes are effective at telling a story, multiple anecdotes still aren't data.

"So it’s reasonable enough for me to conclude that with proper maintenance, the risk isn’t that high until there is further data. And that is unlike other engineering defects in other cars that has a high chance of failure even with proper maintenance and can only be prevented with actual modification."

Key point here is the "for me". If you are cool with it so be it. People different risk tolerances. I obviously have a lower risk tolerance than you. Even though the chances may be low, I would not be saying "Oh pussy feathers" if I needed an engine rebuild. I would be kicking myself for not listening to my gut and buying the newer model. So, for me, I would rather just stick with the 991.2 or newer.

Most of the facts that we operate on in life are formed by anecdotes so I don't really understand your point. In the hard sciences, all "facts" are fundamentally considered provisional. Multiple what you are calling anecdotes, when given by a professional who is seeing these engines day in and day out, is what you use to form "fact". Please remember that these engines are still quite new and therefore even in the aftermarket there has been limited information compared to previous generations. I manage risk professionally for a living. If you talk to a trader and they tell you that a, b, c traded for x, y, z those are "anecdotes" but can be used to form a reliable picture and that is exactly what professionals do.

Wonder if Porsche would take some sort of remedial action, or at least send some warning, if this is any sort of concern for 991.1 owners now surfacing years later from a liability standpoint?

Wonder if they did anything for IMS 996 etc..

my point is the actual failure rate is probably orders of magnitude below a person's perception from reading forums. :)

AFAIK, the four ball wear test is ideal for measuring grease, not oil. I don't think it's a valid way of measuring how good an oil is. It's like saying that petroleum jelly is better than hand lotion because it's thicker.

Good job on digging back almost three years into this thread.

That chart above would be more interesting - nothing withstanding any opinions on the test methodology - if the Mobil product tested was the same formulation that carries A40 designation rather than a random oil from Mobil’s second-best (or third-best) product line.

In the attached used oil analysis which includes data on both Mobil 1 0W-40 and Motul 8100 Xcess Gen2, you’ll notice that after 4K miles on the Mobil 1, the Viscosity index was 11.8. 12.6 is the minimum threshold for a 40 weight oil and M1 in virgin oil analysis is shown to start at 12.9 centistokes. That means from the start, Mobil 1 barely meets the description of a 40 weight oil. It is very thin from the start in order to improve fuel economy (which is what the factory likes to have sit up there for their CAFE standards). After 4K miles, the analysis shows that the viscosity index went down to 11.8 which means the oil has fallen out of grade from a 40 weight to a 30 weight oil. This is not great and perhaps why the metal wear numbers were up significantly over the Motul which had almost 5K miles on it. After 5K miles, the Motul’s viscosity index held at 13, so still a 40 weight oil. It did not shear out of viscosity. I’m no longer a Mobil 1 fan.

https://cimg5.ibsrv.net/gimg/rennlis...23f847273.jpeg

This is not necessarily correct. With respect to the four ball wear test, ASTM D-2266 is for grease and ASTM D-4172 is for oils.

Wow, that is a fantastic result on your last UOA and the numbers appear almost too good to be true! I was using 0w40 with decent results but decided to experiment with M1 5w40 to correct the viscosity and have been happy so far. In a recent Lake Speed video he expresses concern over the high calcium content of an M1 0w40 sample (3,000+) and it's connection with LSPI ( Low speed pre ignition). I don't believe I've ever experienced it and I never lug my engine but I don't believe I've seen an A40 oil with calcium numbers as low as yours.



https://cimg1.ibsrv.net/gimg/rennlis...d509ed131f.jpg

That's not Lake's concern in that LSPI is well documented in tribological literature especially for turbocharged direct injected engines. Avoid oils containing high levels of Calcium and eliminate Sodium. The detergent package and additives utilized in the oil you choose matters very much including other important considerations like the soot dispersant (DFI engines produce soot similar to a light diesel engine). Calcium is the most widely used quite frankly because it's cost effective ("cheap"). There are much better oils than the M1 products.

To be clear, that is not my UOA…I saw that from another forum member when they posted their results. I saw that and decided to switch to Motul and am happy with the oil so far. I haven’t done a UOA yet but I’ve noticed it already burns about 50% less than the Mobil 1 I had in the car before (and I had the 5W-50 in my car which is even a thicker oil than the Motul).

Outside of the Eisen class action lawsuit settlement, Porsche did nothing. They did offer for a short period of time a replacement bearing kit that used a ceramic hybrid single row bearing, but that part shortly was removed from the system and is not available for purchase any longer. I was hopeful that Porsche was going to release service guidelines when their bearing was released, but nothing was ever published and outside of those on the Porsche classic advisory board, I don't think many knew this part even existed.

Same goes for the Lokasil blocks and to a lesser extent the Alusil blocks. We know that they fail and why they fail. But no changes have been made to the new replacements offered by Porsche. It is up to the aftermarket to come up with solutions and provide support for these applications without acknowledgement of the issue by Porsche.

If you were to go back 15-20 years, you'll see my posts about M1 being consistently formulated to the bottom of the spec for a 40wt. And yes, we know it sheers down to a 30wt relatively quickly. This is great for fuel economy.

Like you, changing oils and doing used oil analysis will show how other A40 oils like LM 2040 or Motul 8100 X-Cess are superior to M1 0w40. If you go on the 996 and 997 forums you'll see many UOAs from people who have switched from an A40 oil to Driven DT40 or DI40 with even better results. The proof is in the pudding.

If you are dead set on using M1, using the C40 spec 0w40 is a much better option and provides superior protection from what I have seen compared to the A40 M1.

I would just use the 4 ball test results as a reference point for an oil having a HTHS vis @ 150C and/or for use of friction modifiers, as the addition of latter will greatly skew the results. On its own it's meaningless, but I would expect an oil that does better in these tests to provide superior wear protection.

Yes I am not even saying it's a test that matters -- just that it's not only for grease. In the end my own opinion is that I don't really care too much about how a given oil does in a myriad of tests because the test that really matters is the engine you run it in (although the former should be an indication of the latter). There is nothing better I have found than Driven DI40 but for sure M1 is an oil I would avoid even if it is a PAO ester blend. The proof is in the pudding just as you say.

I can’t remember if this applied to the IMS issue or bore scoring but weren’t the 991.1 turbos not effected by bore scoring? I have a feeling it was the IMS. If it was IMS then please ignore this post.

991.1 turbos have Alusil engine blocks and can (and do suffer from bore scoring). No IMS though.

ah, thanks for clearing that up. I knew it was one if the two.

What is the percentage of 991.1 with Bore Scoring issues? Any 991.2 reported with Bore scoring?

That is pretty bad scoring on there. Are we seeing more and more 991.1 with scoring?

from the 991.1 owners I personally know (very small sample size of 6) 2 of us got bore scoring (1 for sure the other probably). Mine happened under 20k miles and the other person got it around 45k recently (signature ticking sound, sooty plugs and tailpipe, etc. that’s not due to lifters). He just got a basic boroscope done but is getting a better one soon.

best advice I can give to you is if it happens to you just send your car to Deman Motorsports. The 4.5L rebuild has negated any desire to upgrade my car and it smokes 991.1 GT3RS’ on the track. Rick uses nikasil and super high end components that don’t sacrifice reliability.

whatever you do make sure you use new injectors for the rebuild. Injectors are what cause this.

Are we seeing 991.1 C2S, C4S, GTS with scoring only? How about the Turbo and GT3? But GT3 has its own major engine failure.

the scoring cases I’ve seen are a GTS, a C4S, and there are reports of C2S’ as well.

The turbos I haven’t seen issues with. The GT3 engines have finger follower issues and the RS engines are fine (different coating too I believe)

Just out of curiosity
 

How much did that set you back ?

There are no figures I can quote as to how many have scored. The only data I can share is that they make up about 5-10% of all the engines we see.

And who nows how they were driven and maintained?

that percentage is a lot higher than the percentages for IMS bearing, no?

Unless I am reading it wrong and its 5%-10% of cars that come into the shop with issues, and not cars on road

Correct, that is 5-10% of blocks being sent to us for repair are MA1/9A1, and then only the 3.4, 3.6, and 3.8 liter models. We get calls with Macan and Panamera models with scoring, but to date not a single person has actually chosen to rebuild one of those engines. I'm guessing most of those cars end up getting off-loaded or crate engines put in while they are still somewhat affordable. We do see Cayenne V8s too, but they are far and few between, and most come from colder states and Canada.

We no longer service cars at our location. The service shop was spun off as a stand alone business and sold to one of my techs back at the beginning of 2020 and is now run as Speed and Suspension:

https://speedandsuspension.com/

Last I checked, they fail about half of the cars that come in for IMS Solution installs for bore scoring, but granted we do see our fare share of cold weather, so that is to be expected.

For full perspective on the % it might be interesting to know the number of 997.1 motors that have not been updated vs the same number for the 9A1 motors.

The turbos received a different annealing process. Is that a factor?

Are we dealing with straight bore scoring or an end effect of cold seizure?

It's sad but we are seeing more and more 997.2 now with bore scoring as well and everyone was saying they were bullet proof at one point.

Baz reported on these motors some years back, discussing the importance of proper warm-up as well as cold climate challenges.

Also ... Cold seizure, which Baz figured was the primary culprit.

In the first case, we have limited control.

In the second case, it may be luck of the draw. But from what Baz said at the time, if you don't have a problem after X miles, you're probably fine.

Having a 997.2 that burns no oil with 162K miles, I'm hoping for only the second case. So far, I haven't seen data to support 1, 2, or both. Of course, I'll continue a prescribed warm-up procedure regardless.

Additionally, as Jake and LN point out, DFI fuel injector failures could cause problems in a hurry.

We actually offer and recommend cryogenic treatment on the MA1/9A1 blocks. It's best to do this before any work is done to the block.

I will say that I don't think we've ever had a turbo block come in with scoring/seizing, so certainly the different processes carried out by the factory may indeed have helped.

Most are seizing rather than traditional bore scoring, but we do indeed see blocks with scoring that do not have seizing.

Thank you, thank you, thank you for your response.

From what I have heard (not seen), I would guess the scoring goes along with bad injectors. I know you advise using a good cleaner with PEA. Do you have any other advice on caring for the injectors? Or testing the injectors? Or recommendations on refresh intervals? I speak as a 2010 C4S PDK owner with 162K miles running on all original drive train. I'm still burning no oil. I'm planning to do a borescope the next time I change my plugs.

Thanks in advance for any words of wisdom you can share.

I'll tell you what I do with my own modern cars. I don't have access to Top Tier fuels, so I run Injector Defender every other tank. If you run a Top Tier, I'd say run an additive with PEA every 2-3k miles.

The direct injectors are notorious for not coming out without breaking, so I'd just leave them alone. Not like port injectors that are easy enough to swap out. If you do have wonky fuel trim values, then I would for sure dig into why this is occurring.

Excellent information. Thank you again.

FWIW my Indie uses Liquid Moly 5-40 for Porsche Oil changes. I trust these guys!

Add a can or a can and a half of Ceratec or MoS2 to the LiquiMoly per long standing oil threads and UOAs on the 997 Forum.