Royal Purple VS Amsoil Engine Oil

My father had a 66 Dynamic 88 with a 425 2 barrel. I was not old enough to drive but my older brother said it was a brute. I had a 67 Cutlass with the "Turnpike" package with the 400 big block 2 barrel and a turbo 400. It actually was a rare car and I didn't know that when I sold it. Oldsmobiles and Buick had a high nickel content blocks which made them stronger than Chevy and Pontiac (supposedly).

https://www.hemmings.com/stories/2017/01/11/commemorating-oldsmobiles-turnpike-cruisers