bronto

http://www.economist.com/blogs/babba...l/bl/tribology

I remember a discussion here in the past about zinc additives, don't remember the conclusion...

Speedtoys

Interesting observation in there on aviation oil..

My RX8 LOOOOOVES 20/50 Shell aviation oil..granted it uses oil somewhat differently than a 928 engine will to run properly.

I believe also, I saw a thread in here somewhere where someone was using Rotella diesel oil as well.

AO

This has been discussed SOOOOooooo many times here.

There are only a few oils out there that have the level of ZDDP that work for us.

Mobil1 15-50 does and that seems to be the preferred oil among 928ers (there I said it... watch out).

Do your own reserach... it's your motor.

Marine Blue

Ok I hate to start another oil debate but I'm going too..

I'm about to buy some oil for the GT so I can change the oil before storage and I want to know if the latest versions of the Mobil 1 Synthetic contain the right additive packages for our cars?

A few years ago I know that only specific viscosities and types were acceptable, has that changed?

mark kibort

amsoil has more zinc now with their new formula, but its for racing. (doesnt have room for detergents like a good street oil) 15-50 mobil 1 might be good in this respect for street driving, but under high temps, it falls apart. most wouldnt experience this, unless you are really beating your car up or are on the dyno getting oil temps over the 230F range.

bronto

I've been using Royal Purple because it seems to have better pressure in very hot weather (which I need for some trips to Fresno). I just looked up "zinc" and their site and found this:

"Do your motor oils contain zinc and phosphorous?

Yes. All Royal Purple engine oils contain the zinc/phosphorous compound zinc dialkyl dithiophosphate (ZDDP) and are suitable for both roller and flat tappet valve trains."

So, I'm good

AO

Alright... who hijacked Kibort's accout?

AO

How much is suitable?

Speedtoys

Over 230 measured, is hot? Is this...pardon my ignorance, measured in the sump, or after the cooler?

blitz928

Made the switch from 15w50 Mobil 1 to 20w50 Brad Penn for this reason.

hacker-pschorr

All oils have ZDDP

The question is, how much? The old standard was 1100 - 1200ppm while the new standard (GF4 / SM) is 800ppm or less.

I stopped using RP a few years ago, couldn't justify the extra cost with cheaper and proven options like Brad Penn and VR-1 on the market.

It's still good oil, just pricey.

Landseer

So is 15W50 Mobil 1 a reasonable or unreasonable choice?

mark kibort

in the sump so who knows how hot it can get in critical areas.

we race at 230 to 260F ranges (260 on 100F days) and mobil 1 just falls apart at 220F in my experience. I would just assume to use wesson oil in a 928. but what do I know! heck, i only race this darn car every month for years and years and years!

mark kibort

had bad luck with VR1 too, in scots car. amsoil fixed that low pressure problem at high temp too. only kendal , which I dont think we can find any more RP, redline, and amsoil are the only ones Ive tried that dont fall on their faces in high temp applications. however, im sure motul and the other high end synthetics are fine too. mobil 1 is just a walmart brand in my opinion and has a ton of corporate partnership and marketing around it, rather than quality and performance. again, sure, Porsche endorses it, but im positive there is money behind that relationship. Its a "cool" brand. Even I like the look of the logos on my race car, but is it the best for our 928??? doubtful . Is it ok in a street car, sure, probably no problem. race it?? watch out!!

aj986s

Granted, this was about 20 years ago, so not sure if it still applies. But I remember a friend of mine who used to run an SCCA Showroom Stock car, was usually a front runner, and swore by his RedLine racing oil. Before a particular Regional race weekend, he wanted to change his oil, but discovered he'd run out of his RedLine stock. So he contacted his normal supplier who told him he had none to sell, because he was taking it all to SCCA Nationals at Road Atlanta (to sell at a premium of course....). So my friend decides to buy this new stuff on the market, Mobil 1. During the race he ended up with several spun bearings.

I've heard/read that Mobil 1's consumer bottled oil is not the same that's used by pro racers.