That's true, there is a hell of a lot of ass covering in the land of oil recommendations. Gallons of it. They only recommend whatever grade the manufacturer puts in the book. Simply because that covers their arse should anything go wrong. I have asked penrite and Valvoline similar questions before by email. Can I use Synpower in my alloy tec type thing. First answer is they recommend what Holden states.
And I said I don't want to use that, and why can't u use Synpower.??
To which they respond something like well Synpower is a premium oil it would do a fantastic job. But they recommend what Holden says
LoL