Amsoil is some good SHATT! but like John says, the others are good too! I happen to like the Red Line Gear Oil... Run it in my mustang Diff with Ford Friction Modifier. I run Royal Purple with Cheese in my Mustang manual transmission with a bottle of Ford Friction modifier. Truck gets Amsoil in the Transfer Case. I hope it does not let me down! Oo. Oo. Oo.
The american V-twin I own, gets Amsoil 20W-50 in the oil tank. That works like a champ, especially in 100 degree sacramento HEAT!!!