Mobil 1 Castrol Edge (Black Jug) Valvoline Advanced All of these oils are GF-6 or GF-6a, but I recently noticed that the 5w20 viscosity is not Dexos approved. However, they are Dexos approved for 5w-30 and 0w-20. Makes me wonder why? Is 5w-20 becoming an obsolete oil viscosity? (I don't think so) .

is mobil 1 5w20 dexos approved