I did a "somewhat" back to back test years ago going from a conventional Valvoline 10w40 to Royal Purple and picked up almost a tenth but if you don`t keep EVERYTHING the same like; leave rpm`s, engine, oil and trans temps, how can you get a true comparason. Lets not forget corrected altatude, humidity track prep etc............I only run thinner oils like 5w30-10w30 myself.............