They do use the same tappets. Any old school engine like the 4.0, or my Chevy 350 and even my Subaru engines have this issue. After reading the above post from a Shell guy, I was surprised to hear that the cats are fouled by those metals. Mine has not been. I have also had an oil rep from Valvoline tell me that the new formulation was due to most engines using roller cams now. But they again, they put these additives in most of their oil and have the highest amount of them available in their racing oil, which I highly recommend