Based on what? Lab testing for wear protection? UOA's?
Royal Purple is an old-school synthetic oil that is low on film strength and high in ZDDP (Zinc dithiophosphate). ZDDP was once king of the hill in terms of high-pressure anti-wear additives. Those days are long gone now though and ZDDP is not as important as it used to be. This is for several reasons.DO NOT USE ROYAL PURPLE IN OUR CARS!
It has been proven to be incompatible with the metallurgy of our motors and will wear your internals.
Old post, but thank you for the info. I literally bought new oil today and milled this around. I just went to old reliable Mobile one.