i will always use manufacture spec oils. I may add power better gas octane boosters and bolt ons but I will never ever go against what a company reccomends for oil. But from what I hear Royal is a great oil for race engines. I ran it in my 76 monte. 502 s/c bolted to a turbo 400 tranny. That thing made 700hp at low boost 9psi and over 1000 at high 14 psi. And then you add the Nitrous whew what a ride. But that was a bought and built motor.