One thing I will mention that seems to be overlooked is, I have one of those cleanable filter systems on one of my cars, and I changed the oil last night and I cannot believe the amount of crap that thing finds in the oil, of what I consider, to be a really well maintaned engine. It took 40min before I felt I had it totally clean. I will never go back to a bypass style filter for fear all that crap is going to go thru my engine. Where in the world does all that stuff come from....And I did put Brad Penn in, but normally I just run diesel 15-40, but now the diesel stuff is nearly zinc free.