bgiere

Hate to add more confusion to the theories but I saw this and thought it may be helpful.

http://www.bobistheoilguy.com/forums...941647&fpart=1

http://www3.interscience.wiley.com/c...TRY=1&SRETRY=0

gunlover05

all this stuff seems confusing to me...has anyone sorted through all this with confidence and have a recommendation for what oil or additive we should use??

old man neri

That's it, I give up, from now on I am just going to be running olive oil in the engine. I don't understand motor oil anymore.

imcarthur

I agree. The experts go on & on with all of this data & chemical signs & acronyms & somehow we are supposed to make informed choices.

I'll admit, I know nothing about the subject other than the threads on Rennlist & Pelican. The easiest thread for product discovery is Ultimate Motor Oil Thread or Why we hate CJ4/SM oils on Pelican.

The thread author has been keeping a scorecard of the 'approved' oils in the 1st post in the thread:

Brad Penn Racing Oils (same as the old Kendall from the '70s);
SWEPCO 306;
Redline;
Royal Purple;
Castrol GTX High Mileage
Mobil 1 V-Twin MC 20w-50.
Mobil 1 MX4T 10w40
Royal Purple Max Cycle 20w50
Amsoil m/c Harley V-twin 20w50
Castrol Syntec "Classic" 20w50
Valvoline VR-1 20W-50 -it is marked "Non-Street Legal".

Further on in the thread are more specifics since there are multiple Brad Penn oils etc if you wish to wade through it. BTW the Penn oil is: #7119 Penn Grade 1 Racing 20W-50

Ian

Old Man: Check the Pelican - Canada Board for a group Penn oil buy for $38.43 for 12

gunlover05

Now you are talking....I'll just take that list with me next time i need oil...now i'll just go back to sleep...

drew3007

Hello everyone. I am new to the forums but not to Porsches. I have been a Porsche mechanic for some years and my father has owned the local Porsche repair shop my whole life. At the shop, for any air cooled 911s made prior to 1995 we will usually use castrol GTX 20-50. That oil will be good for 5000 miles or 6 months.

For newer 911s (993 or newer) we will use Castrol Syntec 5-40. The 5-40 is a euro grade oil that you can get in the US but you usually have to have your local parts store order it. It is a Porsche approved synthetic and we have found that it works better with cooling that the Mobil 1. That oil will be good for 7500 miles or 1 year.

Please note that the time the oil is in the car is just as significant as the millage. Oil breaks down over time just like it would from use.

The reason why use the GTX in the older cars (we even put it in 356s) is because of the start-up protection it provides. This is the most important factor when you are dealing with older cars.

Insofar as oil additives are concerned, we usually don't use them. If there is valve-train noise then it is just time for a valve adjustment, not an oil additive. We do have a BG oil additive on hand though for 944 valve-train noise and just grumpy old 928s as well. I don't and have not seen a reason to use them in a 911.

That is my very long 2 cents speaking from experience.

imcarthur

Drew

We're talking older air-cooled engines. You might want to start reading that thread:

"I'll also add the caveat that I don't recommend running Castrol GTX for more than 3,000 mi either. In our field testing, it broke down rather quickly (consumption of detergents, Zn, and P) compared to other oils."

"I also hear that Castrol is coming up with a "Classic" line of oils with SG levels of Zn and P - the new Castrol Syntec "Classic" 20w50 is already on their web site. I'm figuring this is the first clear response to our demands for an appropriate oil for older cars in mind from the big oil companies."

Both in posts by cnavarro who does appear to have some knowledge on the subject.

And I repeat, I know nothing, I'm simply the bearer.

Ian

DarrylH

Not to be difficult, but isn't this backwards? A 20W-anything is gonna give worse startup behaviour than a 0W- or 5W-, isn't it? Or am I completely misunderstanding something?

Brads911sc

people are way too obsessed with this whole topic IMHO... I found an Exxon Superflow 20W50 at my local parts house... Its SL rated. They also had an SL (pre 2004 applications) rated Valvoline. You dont need to travel around the world to find oil that was the "standard" for most of the lives of our 80's porsche engines. I have stopped using Castrol GTX at the recommendation of the experts... but good SL rated oils are not hard to find... and you dont need to pay $60 a case for Brad Penn to get a decent SL rated oil...

LaughaC

Brad Pitt sells motor oil? Maybe he can talk my wife into working on my car with me...

Brads911sc

Brad Penn not Brad Pitt. HAHA. That was a good one..

old man neri

Ian,

Ya, I looked at that. Thanks for the thought. I just changed my oil a week ago. I went with an elf synthetic. I got it here locally at a porsche shop. I am not overly obsessed about the subject as some are. No doubt by the time I need to do another oil change all the information, facts, and recommendations will have changed

Cheers!

drew3007

I do understand that it was about older air cooled but since it was in the all encompasing air cooled 911 forum I would post my experience with both oldre and "newer" 911s. That is interesting though. I have not read, heard nor experienced that in my dealings with GTX. I will certainly look into it though. I don't want to say it is wrong or right at this point however.

The lower the first number, the less viscosity the oil is. So a lower number would have less viscosity (thinner) when cold and that provides less start-up protection (thicker provides protection). The second number is actually how much the oil will be allowed to change. So 20W-50 is a 20 weight with an allowable +/- 50 change according to heat. 0W-40 is just that, 0weight. Not recommended at all to be used in older cars.

old man neri

I always thought the second number meant what the wieght of the oil was when it reached 100*C. As for the thinner grades, understand that not everyone lives in SoCal. Run 20W50 up here and see what happens when it gets cold.

bgiere

Drew3007, you have it backwards...A less viscous oil provides more protection on startup...At operating temp a 0w40 and a 10w40 are the same viscosity....