[downs]

I just run diesel oil of some variation rather than adding additives. I do regular oil analysis on my XJ and most of them still have at or over 1000ppm of zinc in them. Rotella being the highest, and Supertech (Wal Mart brand) being right behind them, Delvac had the lowest in my experience so far with right around 800, and Delo being somewhere in the middle.

My go to now is Shell Rotella T4 (regular dino) 10W30 instead of 15w40 that I can get at Tractor Supply for about 13 dollars a gallon. I run it in everything but my wife's van. My last oil analysis on that showed about 1100 zinc and mid 900s phosphorous.

Keep in mind these readings are on used oil with about 5k miles on it give or take a few hundred.