I`ve been reading and searching through alot of UOA`s here. It seems that Pennzoil yb gives the best results out of any oil. I`ve used it and it`s probably one of the smoothest running oils I`ve ever tried. I like it better than any synthetic I`ve used. I know a guy who has a twin turbo 300ZX and he has used yb 20W50 since his car was brand new. He regularly tracks his car and it`s always driven very hard. He did a compression test awhile back and all 6 cylinders show factory spec compression and his car also has the original turbos. He`s just gotten past 350,000 miles on that car. Just makes me wonder what`s in that stuff compared to other oils?