VW's spec for 75w-90 is 501.50 (G50) and when I search on that, I see alot of "API GL4+" that goes with it. I went to the API website but could not find anything about it. My guess is that it has to do with transmissions with integrated differentials. Alot of the oils that have this VW 501.50 spec have very high VI's. I have seen several over 200, the highest being 228. These are lubes like Castrol TAF-X which has a viscosity @ 40/100 = 73/14.4 cSt, which should give very good cold weather shifting. My car calls for the VW G52 oil, and I would love to know how it differs from the G50.
Thanks for any help!
Thanks for any help!