Having went to school years ago with a friend turned engineer for Mobil...I will stick to my Mobil 1...he was testing this stuff when we were in our 20's...pulling oil samples and such...long time ago...it has worked for me...and all my engines over the years were spotless when we had the heads of...the worst I every experienced was Kendall, with Pennsoil coming in a close second...a lot of crude floating around in the bottom of the oil pan....each to their own....