Joe Gibb's Racing, prior to having their own oil made, tested Royal Purple, Redline Racing 30wt, Mobil 1R 0w30, and even Amsoil Series 2000 at one point. Of those mentioned, they found Mobil 1 was best. I know that would surprise many, including myself but that is what I was told. They have a lot of professional racing teams using their oils and that is the best indication of how good an oil is. Mobil 1 wasn't meeting their needs so they had their custom oil made for them by Lubrizol.