KLS

I've not done autocross yet, but it seems like that may be the perfect storm. You go through an inspection, let the engine partially cool, then go through several runs with a few minutes in between. Is that the type of situation that I should avoid?

Gibbo

Spoke with Hartech today, they said they recommend use of Millers NT 5W-40 and 10W-50

I asked which grade would they use for maximum protection from bore scoring and they feel 10W-50 offers better protection from scoring even at cold start. As these guys are considered Porsche gods I shall be going with their recommendation.

7500rpm

Gibbo's question got me wondering, especially when I recently diagnosed my friend's 05 C2S with pretty serious scoring on cylinder #6. I turned my bore scope on to my own #6 cylinder and found 2 lines. The difference in the scoring -
1/ Only 2 lines visible compared to the multiple lines on my friend's car;
2/ His is on the 6 o'clock (lower) position of the cylinder whereas mine is on the upper/non-drive side. In fact, they are at the 10 and 11 o'clock position of the cylinder which seem kind of odd.
I am more curious than concerned about this scoring. Do all engines have them to some extent? I am going to check the other cylinders when I have the time. First picture shows drive side of the cylinder and second picture the non-drive side with the scoring.

USMC_DS1

7500RPM, thanks for sharing... Would you mind sharing which inspection camera you used. I've been looking at this
HF also has a less expensive one with an 8.5mm camera. I believe a 9mm camera or smaller should work to look into the bore/cylinder. Of course, the mirrors tip need to be secured(tape perhaps) so that they don't fall off in the cylinder. That seems to be a recurring issue for some users from what I've read. Looks like another project to add to my list of TTD but an inspection camera is one of those tools I've been meaning to acquire for some years now.

Macster

Let's see.. Hartech which has no real skin in the game knows what it is doing when it recommends some oil and yet Porsche, which I guess I should remind you has its name on the car, knows nothing when it recommends (approves) nearly 2 dozen or more oils.

Interesting.

When some company that spouts this lower t-stat non approved oil nonsense starts warrantying these cars from the outset to say 50K or even 100K miles (my Turbo went to over 60K miles with a CPO warranty) then maybe I'll listen.

Many tests have been done to find the sweet spot of engine oil temperature. Hotter (up to a point) is better. I do not have the exact numbers handy from one such study but below 200F wear increases greatly. In 60 hours of run time at the lowest tested temperature the engine would have been worn out. Twice.

Macster

Almost certainly all IC reciprocating engines have "scoring". The piston and its complement of rings moves up and down the cylinder sometimes thousands of times per minute. What other kind of marks would you expect to see?

The problem is with a bore scope one can't run a fingernail across the "score mark" to get a sense of its depth. While the marks are visible they may have no depth and thus affect the engine no one iota.

Gibbo

Macster

Porsche also operate a 20,000 mile service interval, which is proven not good for these cars.

Porsche are also very interested in fuel economy and emissions hence using a thin oil to achieve this.

Porsche also designed an engine with inherent flaws, rms, IMS, bore scoring, dchunk, cracked cylinders, all mainly caused by a lack of cooling.

Porsche have made a lot of mistakes and are a business who's objective s to sell cars and make money.

Hartech have a lot of skin in this game as do companies like on engineering, such as auto farm, ln engineering, who also sell low temp stats and recommend use of thicker oil.

So no offence but I'd rather listen to the companies who are trying to put the mistakes Porsche made right. Also ask the GT3 guys why they run thicker oils, many going with 10W-60, the answer being the thicker oil gives better protection.

Spoddle

I'm with Gibbo on this one. I just swapped out my thermostat for a low temp one and will be shifting to 5w40 in the near future. I'm guessing these issues are starting to pop up on 997's since they are slowly creeping up in mileage (my car just ticked over 70k).

7500rpm

USMC, I have a Taiwanese product which isn't even branded. I bought their higher spec one with 5.5mm camera. Screen is 3.5" and it has 6 high intensity LEDs on the lens. Min. focus is 80mm, which might explain why my photos are a little blurry. Paid $280 for it, but reseller gave me a 4GB micro SD card for free. I did not use any mirror tip, don't want to drop anything inside, for sure! I was able to get enough curve from the flexible 7mm shaft to get my shots.
Gibbo, sorry to hijack your post. I was answering a question. By the way, I use 5w-50 over winter but will change out to 10w-60 when it gets a little longer.

USMC_DS1

Does anyone know how the p-dealer would determine that a cylinder is scored? Wouldn't they use a bore scope? And what do they look for(criteria?) to determine that the cylinder is scored or scored enough to warrant an engine replacement. Cylinder scoring does seem to occur... I considered purchasing an '06 C2S two years ago which had it's engine replaced under warranty due to scoring. Decided instead to purchase an '08 C2S with original warranty and CPO. I don't believe that my engine has any scoring. No smoke coming out the tailpipe nor any signs of oil consumption... but I'd like to baseline the images of my cylinders and compare as time goes by. Not to mention that if I find something wrong then I'd ask the p-dealer to address it before my CPO runs out next year.

7500rpm

USMC, the OPC that my friend sent his car to said they'd have to disassemble the engine to see what's wrong within the cylinders! Seem crazy when one could just stick an endoscope in for first inspection. Granted, as Macster says, one couldn't tell how deep the scores are but at least you know if they were scored. So our experience is that the OPC does not use endoscopes. I will guess that they use engine compression gage for leak down test but maybe not. They seem so dependent on their fancy PIWIS which doesn't always tell the full story.

jumper5836

My 996 3.6l has a scored cylinder. It still runs but oil consumption is bad.

How are the newer 997.2 engines holding up with regards to scoring?

Luxter

First, Turbo, GT2, & GT3 family engines are not built the same way as M96/97’s and they don’t suffer from cylinder scoring to the same degree as M97 (if at all). Their T-stats are low temp BTW too.
To fully understand cylinder bore scoring issue it is important to remember that we (CX &CXS) are dealing with Locasil cylinder walls and piston skirt coating that tends to get scratched and begin to delaminate during its service life as it comes to direct contact with Locasil surface. I obviously oversimplify the issue, Baz Hart wrote some 72 pages worth of detailed explanation.
It is not the same process as piston seizing in the bore (caused by piston overheating and thus increasing its size inside cylinder). Only one (Thrust) side of piston and cylinder bore gets scored which is top side of Bank 2. Cooling system (its complexity, location of T-stat, lengthy hoses to radiators, etc.) is most likely to blame for it, or specific conditions that cause local overheating on thrust side only. Since bank 2 thrust side heat exchange between coolant and outside of cylinder wall is not as efficient as bank 1 (again very well explained by Baz in guide 5), it suffers from scoring.
Oil itself is not necessarily a primary culprit but plays its role as well. Keep in mind that scoring does NOT occur when engine is cold or during warm up period. It occurs in hot engine under heavy loads and likely at modest (low) RPM’s as well (which has to do with cooling system design again and cooling pump rotational speed and flow rate). In other words your right foot is asking for lots of HP but your engine cannot dissipate heat fast enough to prevent local overheating of cylinder walls.
Baz went nuts describing importance of 160*F T-stat, I am not going to repeat all that.
However, one important statement from his write-up is that as condition (and age) of engine and coolant in particular deteriorates (remember, coolant = lifetime, according to P service manual), system leaks appear or increase (hoses, radiators, coolant pump, etc.) the system itself become more prone to local overheating leading to scoring cylinders.
Hartech also mentions that with miles on your clock increase it is prudent to consider XW-50 grades of oil as clearances in your engine increase and demand on oil increases as well. Those in hot climates may consider switching sooner than poor be$tards living near North Pole such as myself.
Let’s not turn this thread into another “oil thread”. Please keep information flowing and turn flame throwers off.
Cheers,
=L=

Gibbo

Luxter

Thanks for posting, for summer I am now using Millers CFS Nanodrive 10W-50 and in winter I change too 5W-40.

Also gonna fit low temp stat too.

Already have X51 radiator and change oil every 5000 miles and only use Shell Vpower fuel, so done everything to protect engine, time to enjoy it.

Only other thing I might consider is FVD deep sump kit to get another half litre in their as better for track use and helps cool things further.

USMC_DS1

Talk to Rhonda at FVD if you go with the deep sump kit and mention that you're an active RL member. I believe they're still providing a discount for RL members. Here's a DIY write-up if you want to install it yourself. BTW, I believe it adds another 3/4 liter to the oil system. https://rennlist.com/forums/997-foru...l#post10245275