rcg412

A common topic of debate, when I took my 01 C2 in for the 75K service, the mechanic said we are going to switch you over to 15W50... This was at Rennwerke in Elmsford, NY.

Looks like Jim (1999Porsche911) is on to something..?

Ross

cdodkin

Uh oh - now you've torn it!

That's going to put a bug in the eye of the 0W40 crowd

Chris.

Steven C.

[QUOTE=rcg412]A common topic of debate, when I took my 01 C2 in for the 75K service, the mechanic said we are going to switch you over to 15W50... This was at Rennwerke in Elmsford, NY.


Who died and made this guy the oil expert? Everybody just do what you think is right and kill this topic before it gets legs....again

eurotrashed

What about blending 0w and 15w to make 7.5w... a ceasefire/compromise between these two warring tribes?

Alan C.

I've got the whole thing covered. I drained the oil and put Prolong in the sump.

gota911

I'll make extra popcorn for those who want to sit back and watch the fight!

wross996tt

OK to get the fight going...15W50 is water...and it s not recomended by Porsche...now...some popcorn please.

Tool Pants

I have an early Boxster.

And NONE of you stone throwing 996 folks were around back then.

We used Mobil 15W-50. Porsche said to use it. The dealer used it. I still use it and I have a 9 year old car. Proof is in the pudding, at least where I live.

And 7 years later on the various message boards and attending the local tech sessions, I have yet to hear of a single engine problem related to the weight of oil.

For popcorn, I hear peanut oil works, but I do not know the weight.

Adrian

Wrong! This 996 owner was a Porsche owner long before the Boxster was even invented and this oil grade/weight discussion predates the Boxster by at least 7 years with the introduction of the 964 series, along with:
a). The switch at the Porsche Factory from Mineral (Dino) oil to Partial or Full Synthetic oils which occurred in 1989 and
b). The discovery in the 1980s (circa 1986 onwards) that American manufactured oils were causing coking problems in many Porsches delivered to the USA. This resulted in the first of many overhauls of the Porsche (as in the Factory in Zuffenhausen not the PCNA or Dealers) oil recommendations and manufacturers approvals for use in 1989.
Personally I don't give a toss what oil anyone uses in their Porsche, but for new owners of any Porsche be it air or water cooled and under new or used warranty, I recommend you follow the oil recommendations provided for your model in the owners manual and try to keep up to date with the "Approved Oil Recommendations" issued periodically by Porsche.
After the warranty has expired and you feel comfortable deviating from these recommendations based on "Porsche Owners" experience written on various internet forums, blogs or magazine articles then that is your decision.
As for the statement:
I would love a dollar every time this kind of statement has been used to justify any position in an argument. The reason that this statement can be made is that nobody has every bothered to investigate if there are any genuine advantages or disadvantages when using thicker oils.
What I can say is that data is being collected about various engine problems versus oil grade and weight from around the world to see if there is any relationship between the oils used and common Porsche engine problems. This is being done for aircooled and watercooled engines only for the 964 to 997 series of 911 at this time. Somebody else can do the rest. This will take quite some time to put together, but I am looking forward to seeing where this leads, if anywhere, but we will never know until we try.
For the record I use 0W40 because of the temperature conditions in Switzerland, but I would never consider using thicker oils anyway. I like my oil to flow when I start a cold engine, but that's just me.
I have only ever used 5W 30 and 0W 40 in all my Porsches. Once I had to top up with a slightly thicker oil on a visit to the UK because what I wanted was not available.
Ciao,
Adrian

nycebo

Wouldn't it be the case that at temperatures at or slightly below freezing (down to -10 degrees F), both oils will operate about the same (check the chart below)?

Indeed, the guys over at Car Bible offered the following which makes a ton of intuitive sense:However, I think that the reason Porsche uses the 0W-40 instead of the 15W-50 is because the 996 motor has a lot tighter clearances than in past motors. Thus the lower weight oil reduces friction and drag in the motor and thereby increases horsepower and fuel economy. But, I don't think that anyone is going to have any problem using the 15W-50, particular in climates where it never gets below freezing (indeed, I use it in the summer months here in NYC). Indeed, I've read that for sustained high load, high temperature driving, it's preferable (click here). But, unless you're beating on the car regularly, I'd likely stick with the 0W-40 year round unless you call Miami or LA your hometown (ah, sun year round...what a life) or track your car a lot. Indeed, that's what I'm going to do this winter, after researching this issue the past few months, and stick with the lower 0W-40 weight next summer.

And for all you guys who get tired of these wars, then stop reading. The reason that they continue is because a truly objective conclusion has never been reached...hey, just like in the Middle East.

rcg412

I looked in a 1999 Owners Manual, and a 2003 Owners manual and BOTH manuals recommend 15W50 in >50F and <50F temperatures..... So if the manual is wrong, why didnt they change it in 2003.

Ed's chart makes an excellent point... the 15W weight is essentially identical in >-10F! What I have observed is that the 996 runs HOT (especially 99-01)... and as my temp gauge in nyc traffic creeps right of 180F, the oil pressure drops... a lot, easily seeing 1-1.25bar, only when temp is normal does the oil pressure rest at 1.5... that thin of oil cannot be good in the long haul.

Ross

Adrian

Ed,
I use 0W40 because 5W30 is no longer available from Mobil here. I stick with Mobil because they provide a one year guarantee on all their products if you use them during your service.
I have read all the data you have posted many times before. They are full of theory and devoid of practical facts. This story will never be solved until practical experiments are done on real engines and real wear comparisons made.
One important fact is that the data presented in your post and in the one from Ross presenting his owners manual is that it "only" applies to the USA.
My German owners manual has a completely different set of oil recommendations with the thickest oil recommended for Summer being 10W 40. 0W 40 is recommended for both summer and winter. 15W 50 is also not available here either. I have not seen it in other European countries either, but that does not mean it is not around.
The other issue is the confusing information coming from Porsche. Their oil recommendations from Jan 1st 2005 which were posted to this forum a while ago, no longer show a 15W 50 oil recommendation for all Porsche models from 1985 onwards. Porsche also say that Mineral oil is no longer approved for the Porsche engines, whereas the American 996 2003 OM lists Mineral oils.
This was a huge argument among the 964 owners because Mineral oil was taken off the list here in Europe in 1989, but remained in the USA for over a decade longer. American dealers were receiving their customers 964s filled with Shell Synthetic oil, the 964s were being drained and refilled with American made Mineral oils. This practice continued long after Porsche signed their contract with Mobil at the end of 1992. The Mineral oil guys still go after the Synthetic oil guys to this day just like the 0W 40 versus 15W 50 guys.
One other important point which does play a part is that American oils are significantly different in blending and quality as compared to European oils.
Let the battle continue, but I will stick to what is in "my" owners manual and what is available.
I also never assume to think what Porsche Engineering is thinking, they are German.
By the way my main interest in this subject is not necessarily the engine wear issue because this will take years and years to monitor. A project which I completed in my last job as the Engineering Manager for an Airline was to see what was causing chemical build ups in areas of our engines that were found when they were pulled apart at overhaul. We also noticed that our engine oil consumption rates were increasing, reducing our overhaul times. Cutting a long story short, I discovered that not all oils were oils, not even from the same manufacturer. The additives used were different and one manufacturer and one of their brands was particularily bad. We also found that some oils were killing seals faster than others. This took five years to complete and my interest now is with the Porsche Secondary Air Injection systems (CEL). How the ports get clogged up with burnt oil residue and which oils cause the really hard, have to drill blockages and which ones if any don't. I am sure that the Synthetic blends of oils we use in our engines contribute to such issues.
Ciao,
Adrian.

jb26jb

Just my own observation. I ran 0-40 until this summer when I tried 15-50. I experienced start up lifter clatter with the the 15-50 that was not present ever with the 0-40, which I switched back to shortly after.

Adrian

JB,
This is one of my concerns. This first showed up on the 993 when they fitted hydraulic lifters. Not an issue when everything is nice and warm, but an issue when everything is stone motherless cold. These are the things that lab rats and their tests never show up.
One argument about using thick oil is that it sticks and stays. I have not seen any verifiable genuine evidence of this so to me it remains a theory.
I am also concerned about over pressurising my oil system. In an emergency once many years ago back in Alice Springs I had to add some aircraft engine oil to my old beater. It blew the oil cap clean off and left a nice dent in the front lid. not that I expect Porsche recommended oils to do this
Ciao,
Adrian.

nycebo

Adrian, those are two VERY INFORMATIVE posts. Thanks for taking the time. Even though I can see the merits of using the heavier weight motor oil, like you, I'm going to go back to using the 0W-40 full time/year round. I guess the point is that Porsche may not know everything, but they sure as heck know a lot more that I do...despite my efforts to educate myself more on the subject. Moreover, I wonder if the thicker oil actually makes the engine work harder and thus wear it down over time rather than prophylactically protecting it as common sense might indicate. Anyway, thanks again for your post.