I run royal purple in my race motor, I personally don't have any experience with wolf's head other than hearing nothing bad about it, I know some like Mobil 1, some Brad penn, on and on. I am sure they are all great, and will pass one form of test better than the others, the main key is no matters who's name is on it, make sure it's of good quality. There is some cheap junk oil out there, and even more important than the name on the bottle is make sure oil of some kind is in there, anything is better than none. Alot of ppl nevery pull that long skinny stick ever