JW51's post is why I have stayed away from using the Tractor Supply mineral oil in my Eaton H052 rear end. I'm no rear end expert and no oil expert, but literature available from the GM Heritage Center states that the Task Force rear ends except for the real, real big trucks are all hypoid rear ends. So that's why I never bought the stuff before and stuck to the 90W Quicksilver High Performance Gear Lube. Now, for all I know, the Quicksilver stuff is also mineral oil, but not that I have been able to tell from the Mercury literature.
That being said, I was at Tractor Supply over the weekend and bought a jug of the 90W mineral oil! I guess I'll save that for trannies and stick to the Quicksilver 90W in the rear ends until someone has better advice.
Good discussion...thanks,
Matt
From what I've found, the high performance is synthetic, and premium is not. But I can't confirm for sure
