at -35C they are closer to 5w30 and could produce faster flow, above that it doesn't matter as the oil pumps a fixed volume of oil every revolution.
Originally Posted by moonlightblue
So there wont be difference in terms of consumption between two 5w40 oils where one of them is C3 and the other A3B4? Other question is that would it make more sense to use mobil 5w50 FS X1 for the turbo and other lubricating parts instead of conventional 10w40, as 5w50 sounds like it is closer to 5w30 and 5w40 in terms of fast flow on cold starts? Mobil 5w50 Peak Life had Vw505 approval at least which is not VW502, however in most oils VW502 and 505 used together. But Mobil 5w50 FS X1 which is the only 5w50 available here does not even have VW505 approval. I have also checked the specs of Mobil 5w50 Peaklife versus FS X1, but I am unable to reach to a conclusion. Is there much difference in terms of protection, consumption, thickness, reliability between these two versions of Mobil ?
Originally Posted by dlundblad
I would try a non VW502 such as a conventional 10w40 A3/B4 and give that a try if a 5w40 A3/B4 VW502 is not working for you. I would not expect to see much of a difference in terms of consumption with a (mid SAPS) C3 A3\B4 vs a (High SAPS) VW502 A3/B4 especially with European fuel. US fuel is a different story.