Quote:
Originally Posted by TrackClub
MJK: BOTH 0w40 and 5w40 dexos 2 oils have been certified by GM as good for BOTH street and track duty. 5w40 dexos 2 is NOT track ONLY oil! 15w50 is.
Moreover id argue that 5w40 is a much better summer oil to provide motor protection during hot summer vs cold winter starts. Especially in hot climates.
IMO there is nothing "magical" about the Mobil 1 0w40 except it now gives GM dealers ability to service GM performance cars with dexos 2 oil vs old 5w30 which was street only. Thats it!
Where do you get a notion that Motul has some additives that are cats unfriendly???
I think folks are reading way too much into this GM ***dealers*** marketing release and jumping to huge conclusions based on unjustified assumptions.
NB Corvette Racing team uses Mobil 1, Valvoline and Motul as their choices for lubricants. All three are top notch companies. And all 3 make GM certified top quality dexos 2 oils! And THAT is what GM recommends to be used in our cars in either 0 or 5w40 spec.
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I have daily driven on the 5W40 Motul X-Clean 8100 (Dexos 2), although it could be a coincidence one of my primary cats had to be replaced under warranty after about a year of running that oil exclusively. The manual only states that the 15w50 ZL1 oils must be changed back to the non track oil after an event so you could assume that its safe to run the Motul year round.
My decision to run the new Mobil 1 is based on 2 things. First the oil was specifically engineered with our GM LTX engines in mind, the other oil options may meet the dexos 2 requirements, but they weren't specifically engineered for our engines. You can choose to believe that its marketing hype, but I don't feel it is. Secondly, the new oil is branded as Emissions Systems Protection. I'm certainly not a chemical engineer, but I think that my cat potentially getting clogged by the Motul and the fact that this new oil tested on our cars is branded "ESP" isn't just a coincidence. I believe they found that a certain formulation was required to give high temp protection on track without clogging up emissions equipment.
That being said if my Cat never was replaced and I didn't hear of anyone else having such an issue, I would likely run the mobil 1 once to see if it ran different temps then switch back to Motul if the price gap was significant enough.