dlpalumbo

My shop is recommending I go to conventional oil (instead of the Mobil 1 15w50 I have been running) because, "Its what the car came with". The owner is not a 964 fan (they almost bankrupted Porsche, etc) but his shop is the best around. There is a small leak around chain cover and they mentioned Castrol 20w50 as the go to product to reduce leaks. Not wanting to argue, we all have heard plenty of comment on this topic, I decided to search out the specs on the Castrol product because if it has enough zinc, I'm OK with it. I couldn't find anything from Castrol, but what I did find was a wear test conducted by an SAE engineer for dozens of oils. The results include max pressure and zinc, phos and moly ppm.

The Castrol is fair (#12), but zinc is low IMHO at 610 ppm. PSI levels range from Penzoil Ultra 5w30 at 115k to Lucas 30wt break-in oil at 50k. The best conventional oil is Valvoline NSL at #5 which is non street legal, but followed closely by Valvoline VR1 at #7. Both are 10w30 which, again seems a bit light (Comments?). Mobil 15w50 comes in at #68 due to relatively low psi rating (70k). Note #79 which is ZDDPlus added to Royal Purple 20W50 according to manufacturer's recommendation. The psi rating dropped 24% with ZDDP added. This is a good example of additives messing with oil formulation. There are other examples in list.

The PDF file is attached. Enjoy,

Dan

EDIT: For a more info on source and possibly more up-to-date data look at source's blog here.
Here's a quote from the blog:

In recent years there have been entirely too many wiped cam lobes and ruined lifter failures in traditional American flat tappet engines, even though a variety of well respected brand name parts were typically used. These failures involved people using various high zinc oils, various high zinc Break-In oils, various Diesel oils, and various oils with aftermarket zinc additives added to the oil. They believed that any high zinc oil concoction is all they needed for wear protection during flat tappet engine break-in and after break-in. But, all of those failures have proven over and over again, that their belief in high zinc was nothing more than a MYTH, just as my test data has shown.

There's a lot of info in the blog. It seems to support the author's contention that high zinc levels are not required to get the protection flat tappets need. Only wear protection above 90k psi. If this is indeed the case, the Castrol 20w50 at 96k psi would provide better protection of cams than Mobil 1 15w50 at ~70k psi.

This is going to require a much closer reading.

John McM

Out of interest, did they explain why oil leaks reduce by changing brands but not weights? The timing chain cover sealing is via simple gaskets. If the oil viscosity is the same why would a different brand leak less past those gaskets.

anto1150

Because real viscosity is not strictly connectec to oil weight. Different brands may differ in viscosity on apparently similar oils.

HDA

Yeah without further going into ANY of the results, I am not trusting the source.

Who is 540RAT? Is it this guy ? https://540ratblog.wordpress.com/201...-test-ranking/
talking about flat tapped American V8s?
How does he have access to the testing equipment? Where did he source the oil? So many questions...

Mobil1 0W-40 for me.

Steve Weiner-Rennsport Systems

You're gonna buy a lot of parts at rebuild time.

Railmaster.

The shop mentioned above recomended change from 15-50 to 20-50 from what I can read? No specific make recomended by the shop but they mentioned Castrol?

Notice that Porsche themself now recomend their own 10-60 for the 964!

Love oil threads!

Railmaster.

0W-40 i a air cooled engine?! That's certainly Your choise! Not mine!

Bill Verburg

JMHO, But I'd look for another shop.
Factory fill for 964 when it was new was synthetic oil
Jason Andreas posted this a while back


but M1 15w-50 was an acceptable alternative at oil change time

What has changed since those days is the reduction of ZDDP due to catalytic converter longevity issues.

ZDDP(Zinc Dialkyl Dithio Phosphate) has as it's active components Zn(Zinc) & P(Phosphorus)
An associated factor in engine wear is oil temperatures either too hot or too cold accelerates wear as ZDDP is temperature sensitive, you want the oil to be at least 85C(185F) but under ~115C(240F)

A further factor is the addition of more aggressive aftermarket cams in some cases which will want a higher level of ZDDP

Not all oil has suffered critical reductions in Zn & P if you do some research you can find oils w/ the correct viscosity 5w40 to 15w-40 and ZDDP levels 1000ppm minimum. 1200-1400ppm min for modified engines w/ racier cams

to narrow your search read the fine print on the oil cams, any oil marked API SM/SN, ILSAC GF-4/5 or ILSAC CJ-5 in grades SAE 0W-20, SAE 5W-20, SAE 0W-30, SAE 5W-30 and SAE 10W-30 cannot have sufficient ZDDP

M1 0w-40 which was Porsche recommended replacement oi has the min 1000ppm
M1 15w-50 has ~1200ppm
M1 V twin has ~1600ppm note that too much is as bad as too little
M1 Racing 0w-50 has ~1750 but lacks the detergent package essential for street use, oil change interval is every few hours.

dlpalumbo

In addition to viscosity not being equivalent to weight as mentioned above, I have read on these pages somewhere that when synth oils first came out, they didn't have additives to treat seals and gaskets like conventional oils did. This may have led to early bias against the use of synths as they might have leaked more. Also, I was thinking that synths may be more prone to leak past rocker shafts (I was stunned to learn stock engines didn't have seals on these shafts). I dont know what the ancient history here is but I get the same recommendation from the shop owner to run what was the original fill. And yes I know later years ran synthetic oil. The shop owner has 45 years in business and believes he knows it all, but I am teaching his tech a thing or 2 about the 964 though. This shop is my only option besides dealer. I am giving this shop a try after a terrible experience at only other alternative.

dlpalumbo

Take a look at my edit to original post for link pointing to source's blog. This has source's creds plus most current info.

There's a lot of info in the blog. It seems to support the author's contention that high zinc levels are not required to get the protection flat tappets need. Only wear protection above 90k psi. If this is indeed the case, the Castrol 20w50 at 96k psi would provide better protection of cams than Mobil 1 15w50 at ~70k psi.

This is going to require a much closer reading.

Mixter

Agree with lots of questions???? If you check out this 540ratblog link and do a word find search for "Oil Extreme Concentrate Additive" it comes up 40 times. Just might be pushing this stuff.

HDA

dlpalumbo

And if you read what you searched for you'd have found:

. The “Oil Extreme” Oil Company was so impressed with the detail and accuracy of my oil testing, that they wanted to hire me to perform product development research testing for them. That was clearly a major endorsement of the testing I perform. But, I declined taking any money from them, because I won’t be tied to any Oil Company by money. That way I can maintain my independent and unbiased status. I report the test results just how they come out, good or bad. And there is no way I’d allow any Oil Company to influence anything I report. I did however, agree to perform testing for them for free, along with other testing I perform. And those results will be posted along with other test results.

dlpalumbo

The author​​​​​​ makes a point of stating that both synthetic and conventional oils can provide very good wear protection. He has a section on oil life I haven't read yet, but consider most folks with high performance engines will change oil frequently, so better life time of synthetics could be a moot point in that case

Mixter

I actually did read this and was wondering whether it would be brought up. He seems to really put in a good effort to justify himself. If you're testing for free why not compare other oil additives? So much testing with just one company's product (40 x) and then claiming you're not promoting them. So are there more question? or is that just a clever way of marketing?!