well gm also says dex cool is the way to go and we all know how that ends up,
schaeffers is the only oil im aware of that wil float bearings with zero oil pressure and its not on the list so ya know
fyi Napa branded oil is Valvoline in a napa wrapper just so save you a little $$$ also had a castrol oil rep tell me all this "specially formulated" oil is just the same oil they have always produced, like a synthetic blend might be better for high mileage so they call it that
and i believe orileys is havoline cant remember them all any more
Rlong first off i would be using 5w30 because that is what the vehicle calls for. i also feel that you should use a synthetic blend unless you have ludicrous miles. i would be using full synthetic if it was new. using 0w30 is fine as long as it is not freezing out but i don't know why use a thinner oil when losing oil.
Don't use Royal purple. Ames oil was the first in sythetics. Stuff was used for aircraft back in the day if my memory serves correct. It's the king IMHO... I used to get it from GI joes but they have shut down the stores in my area. I would be my first choice.
I now use Mobile1 5/30w spring thru summer and 0/30w in the winter.