I run royal purple 10 w in my race engine 499, and in my other 499's that are under 800 hp I have always run penzoil straight 30 weight. But it is z7 high sulfer I think it's called and getting very hard to find. Never had a failure, but street use I changed it every 300 hard miles and track use I changed it every 20 passes. But it never failed under extreme conditions. On our big 3500 hp blown injected engines in the demon and draggster my partner and I bought/built and he runs, we use 3 weight royal purple for less drag. I believe royal has a zero weight also. I forget the weight we use in the rear ends but it's less than 10w too.
