Slow RSA

+1 for Motul Classic 20w50, car is used as race/track car only

964Luftballoon

I agree Technology has changed. But danngit don't mind the old man part of me over here waving his cane in the air! LOL

Ken D

964Luftballoon

HAHAHA That's exactly what i was thinking about.

SR20Fastback

Not sure if you were keen to this, but after Brad Penn sold/rebranded, they changed their formula and I believe lowered the ZDDP fairly substantially. You may want to have another look at the levels before you commit again

964Luftballoon

I wasn't aware. Thanks for sharing. I'm due for my every 5k oil change soon. I should see if I can send it out to BlackStone?

SR20Fastback

Never feels like a bad idea, although I've never personally done it.

mby

Easy, if you are inclined to follow Porsche Classic's advice @ https://www.porsche.com/usa/accessor...hts/motoroil/: "Developed as a 10W-60 oil for air-cooled 911 models with a displacement of up to 3.0 liters"

heliolps2

Look into Driven DT50 oils. made for air cooled engines

Bill Verburg

Some oils have changed over time

what has not changed is what the motor needs for long life and good performance

The owners manual lays out nicely what weights to use

the big change over time has been the reduction in ZDDP due to its effect on catalytic converter life expectancy

fortunately the oils our air cooled cars need have been left out of that particular fray to to the extent that each manufacturer can decide for it's self what the composition of his oil will be and that includes ZDDP levels

back in the day when a 964 was new the API standard for ZDDP levels in oil was in the 1200 to 1800 PPM range, most oils except break ins were at the lower end

API SH reduced that to the 1100 to 1300 range
and API SJ reduced it further to below 100, and that's when the trouble started.

Owners started to put the boutique oil of their choosing in the cars w/o determining the actual ZDDP levels, and disaster followed, one example was cardiologist neighbor of mine w/ a brand new 964 in which he put Castrol 5w 60 because he had always used Castrol before, he needed a a full rebuild 3yrs and ~30k miles later

So do your HW, you want the weight specified by your owners manual( full synthetics have more leeway wrt that) and ZDDP in the range 1100 to 1300ppm, If the manufacturer of the oil won't provide that info move on as there are several suppliers of suitable oil who will.

LM964

Maybe by the same token, those without any cat (most/many in the UK) it's not so critical(?) Was that the only or main reason? But again, as you say, most fully synths will have an acceptable ZDDP range so maybe less of a big concern.

Interestingly, when I go through the range of Millers fully synth 10W50 oils I have used on the 964, the same oil grade does have more than one API category - from SM to SL (2010 or older to 2004 or older).

Bill Verburg

API has 2 separate and unequal oil classifications
1) Has the Starburst label, these are all light weight oils which are not suitable for our cars due to weight and mandatory reduction of ZDDP to levels that are highly detrimental to Air Cooled use



The older donut label which is the arena in which all the oils for our Air cooled will reside, but w/i that regime each manufacturer is free to mix and match packages such as ZDDP to his liking, some freely publish what they do, others try to keep it a deep dark secret.. JMOHO but I refuse to deal w/ the secretive types. I also like to buy locally rather than over the internet. The best oil for these reasons for my is M1 15w-50, which has been the only oil in my 2 toys for the last 30yrs. What's best for you may be different, mostly based on availability


W/ or w/o a cat makes little difference except to the auto manufacturers that have to provide a 10yer emissions warrantee on new cars, That is why new cars are designed for the light weight Starburst oils, ours were not, even those that came oe w/ cats like late SC and up

LM964

Interesting info Bill - thanks for the detailed explanation, good to know.

No_snivelling

Bill, can you please clarify your statement "So do your HW, you want the weight specified by your owners manual( full synthetics have more leeway wrt that) and ZDDP in the range 1100 to 1300ppm..."?

I believe this means that synthetics have more leeway in regards to oil weight only. In other words, synthetics do not have any more leeway when it comes to ZDDP levels.
Please correct me, if I am mistaken.

Bill Verburg

Correct 15w/40 synth will likely be as good or better wrt pumpability and protection at high temp and speed as 20w/50 mineral