Royal purple is shit oil. That is not speculation. I have seen the oil lab results.
I have been using royal purple in my service van for the last 120 000 kms. It now has 435 000 kms on it. I have taken the oil to 20 000 kms before changing it and it was down ONLY one quart and barely dark. It is a consistent oil that runs noticeably smoother in my work van(that takes a beating all four seasons from 35 c down to minus 30 c starts). And now it makes a noticeable difference in my Shelby. It may not be the best oil but its the first oil that I have noticed a difference in more than one vehicle. After so many oils running through my car, RP has made it run best ie; diff is quieter than my fathers Acura (no noise/whine what so ever) not to many Shelby owners can say that. Proof is in the pudding and my pudding has never tasted better.:burnout:
One of the RP results in the oil thread that was mentioned earlier was mine. I would definitely not use it again.