But there will be an extra special feeling knowing you have a porsche GT approved oil protecting your engine lol
New Mobil 1 C40 GT 0W-40
- Thread starter Indyxc
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Interesting that the FS KV100 is nowhere near what the PDS shows (13.8cSt)
But, taking these results at face value, shear (%):
FS: 10.64%
ESP: 2.9%
C40: 3.88%
SC: 7.98%
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We obviously can't ignore the fuel, but that's 10.07% visc loss, which is considerably more than we saw with the KRL test.
On the bright side, at least with some types of VIIs, it was found that the %HTHS loss was roughly 1/2 of the %KV100 loss. I did a quick search for the study and didn’t find it but did find this excellent discussion from 2012 on BITOG. Thread
It would be good if someone finds a study so we can see the dependence on the VII type. I suspect at least some of the more shear stable M1 0W-40 variants use star polymer VIIs or some other type more shear stable than M1 0W-40 FS uses.
One reason why Porsche mandated this new oil could be DLC coatings on the finger followers in it's GT engine.
All post-Mezger GT engines seem to have DLC coatings.
Very Interesting that in a recent video, Lake Speed Jr. mentioned that certain DLC coatings do bad with ZDDP and some DLC on DLC coatings don't need ZDDP at all and the oils for these engines can be completely ash-free formulations.
From 17:40
Digging through recent journals, that seem to be the case.
https://www.nature.com/articles/s41467-021-24766-6
Softer variants (hydrogenated a-C:H, a-C) of DLC do ok with ZDDP while harder variants (hydrogen-free ta-C) do terrible due to ZDDP cold welding allowing sulphur doping accelerating damage to the coating. Interestingly, some papers show that MoDTC is bad for DLC as well.
https://link.springer.com/book/10.1007/978-3-319-14771-0 has more info on these coatings and tribology for those interested.
Maybe that's the reason why C40 GT has special formulation?
The ZDDP ppm seems a touch lower in C40 vs ESP X3/X4 looking at
(could be just testing variation too)
Interestingly, Corvette Z06 claims to have DLC coatings too on it's finger followers.
All post-Mezger GT engines seem to have DLC coatings.
Very Interesting that in a recent video, Lake Speed Jr. mentioned that certain DLC coatings do bad with ZDDP and some DLC on DLC coatings don't need ZDDP at all and the oils for these engines can be completely ash-free formulations.
From 17:40
Digging through recent journals, that seem to be the case.
https://www.nature.com/articles/s41467-021-24766-6
Softer variants (hydrogenated a-C:H, a-C) of DLC do ok with ZDDP while harder variants (hydrogen-free ta-C) do terrible due to ZDDP cold welding allowing sulphur doping accelerating damage to the coating. Interestingly, some papers show that MoDTC is bad for DLC as well.
https://link.springer.com/book/10.1007/978-3-319-14771-0 has more info on these coatings and tribology for those interested.
Maybe that's the reason why C40 GT has special formulation?
The ZDDP ppm seems a touch lower in C40 vs ESP X3/X4 looking at
(could be just testing variation too)
Interestingly, Corvette Z06 claims to have DLC coatings too on it's finger followers.
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It's hard to say.
Mobil 1 Supercar 5w50 has high ZDDP with medium moly for DLC parts in the Corvette.
Mobil 1 C40 GT is now recomended for GT cars with DLC finger followers, and steels cams and some DLC coated cams.
991.1 cars had DLC finger followers, and towards the end of the 991.1 GT3 RS they coated the cams. The final "warranty" replacement engine for all 991.1 cars had finger follower and cams with DLC.
I am going to dig into the journal tomorrow, but the TLDR is PAO without ZDDP is best?
I decided to try driven DI40 now. High Moly MPAO, with medium ZDDP, low dettergents.
Mobil 1 Supercar 5w50 has high ZDDP with medium moly for DLC parts in the Corvette.
Mobil 1 C40 GT is now recomended for GT cars with DLC finger followers, and steels cams and some DLC coated cams.
991.1 cars had DLC finger followers, and towards the end of the 991.1 GT3 RS they coated the cams. The final "warranty" replacement engine for all 991.1 cars had finger follower and cams with DLC.
I am going to dig into the journal tomorrow, but the TLDR is PAO without ZDDP is best?
I decided to try driven DI40 now. High Moly MPAO, with medium ZDDP, low dettergents.
The answer is that no one outside Porsche knows. Only Porsche knows if the DLC coatings they chose are compatible with the particular forms of ZDDP and moly additives they specified that oil to use. This is why people are taking a gamble using an oil that does not meet any approvals in a somewhat exotic engine. LSJ is a smart guy but I doubt he or anyone at Red Line etc know if their oils are compatible long term with the coatings Porsche is using.
Yeah. I'm just thinking out loud here. Only someone with definitive data could confirm it.
As most wear happens at cylinder liner-piston ring before cam-bucket, maybe balance of formulation is needed.
Surprising to see Porsche and Chevrolet recommendations going in opposite ways.
More info on the type of DLC coatings from manufacturers would've been nice.
C8 uses iron liners and DLC/PVD coated rings too. Porsche does PTWA iron liner i think, not sure about the rings.
There's no TLDR I can come up with
Good info, thanks for sharing. Well I certainly would only use the C40 GT oil in this case.
Being there was a collaboration between Porsche/XOM on this oil I wouldn't consider anything else.
I think you're giving them too much credit.
If you look at the history of their specificaitons:1. Spec'd Mobil 1 FS A40 for 991.1
2. Spec'd Mobil 1 ESP X-3 C40 for 991.2, made strong claims if you ran C40 in A40, you voided your warranty.
3. Spec'd Mobil 1 ESP c40 GT for all 991 generation GT cars. We know the oil is almost identical to X-3, which prior would void your warranty in a 991.1.
In the 991 generation there were DLC finger followers, in most applications on steel cams, but in some later applications on DLC cams. Their oil recomendations and use of DLC varied signficantly in this generation. It would be very suprising that after 4 years of the engine of the 991 generation they found Mobil 1 C40 gt was the right oil 4 years after the end of this generaiton. Granted the 992 engine in GT cars is basically the same as 991.2 engine.
We do know that ESP X-3 and now C40 are very shear stable. That's a positive direction vs. FS.
I can confirm that on the c8 z06 one of the specifc reasons for Mobil 1 5w50 Supercar developement is to protect the finger followers and cams. It's a good oil, but even the folks that developed it mentioned to me that is a good, but it had to have a price point, and there are better oils out there.
Edit: Very anecdotal the company who has the most experience with the 991 engine platform in the US, and is now in testing of a "finger follower fix" for the GT3 platform recomends Amsoil Euro FS 5w40. VOA below. It's almost zero moly, medium zddp oil. Their fix though is to convert the 991.1 hydraulic lifters to solid, and add oiling to the follower like the 991.2 came from the factory. The prevaling theory on why the 991.1 has higher wear between the FF and cams is at very high rpms the FF and cam have a following error and have micro collisions, over time causing cam/ff wear. The solid lifter is suppose to fix this. THe band aid in the 991.1 GT3 RS was to add oiling and reduce rpms. It seems to have worked. A friend and I started a engine database and the GT3 RS engine data seems to point in the direction that it worked.
https://rennlist.com/forums/991-gt3...-991-1-gt3-and-gt3rs-engine-pdk-registry.html
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I agree. If only they'd disclose something.I think you're giving them too much credit.
1. Spec'd Mobil 1 FS A40 for 991.1
2. Spec'd Mobil 1 ESP X-3 C40 for 991.2, made strong claims if you ran C40 in A40, you voided your warranty.
3. Spec'd Mobil 1 ESP c40 GT for all 991 generation GT cars. We know the oil is almost identical to X-3, which prior would void your warranty in a 991.1.
In the 991 generation there were DLC finger followers, in most applications on steel cams, but in some later applications on DLC cams. Their oil recomendations and use of DLC varied signficantly in this generation. It would be very suprising that after 4 years of the engine of the 991 generation they found Mobil 1 C40 gt was the right oil 4 years after the end of this generaiton. Granted the 992 engine in GT cars is basically the same as 991.2 engine.
We do know that ESP X-3 and now C40 are very shear stable. That's a positive direction vs. FS.
I can confirm that on the c8 z06 one of the specifc reasons for Mobil 1 5w50 Supercar developement is to protect the finger followers and cams. It's a good oil, but even the folks that developed it mentioned to me that is a good, but it had to have a price point, and there are better oils out there.
Maybe they are discovering things as they go along requiring different formulations.
Remember seeing a lot of 991.1 engines having valve train issues.
Most of them seemed to be fixed by 991.2. They even added additional oiling supply for crank.
992.1/.2 engine is basically the same with ITB's and other emission stuff added.
Next engine design would be interesting with next Euro forcing lambda=1 throughout the rev range.
The general thought is the current 2005 992.2 GT is the last NA high reving 6. They had to add 2 cats, and reduce torque to pass emissions. First time ever a GT car lost torque. Word is next generation is hybrid turbo or hybrid electric.
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I had already communicated this information since the introduction of the new c40 gt specification.
It is mandatory for all GT engines.
So it is also for the racing cars, which several times with A40 resp. C40 release was running. These may now only be filled with c40 GT.
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I had already written it here in July 2024.
just curious, did you have any info? or any insights from german forums?
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