Just wanted to pass this on. Back in college, in 1973, a frat buddy had a 1968 Mustang GT notchback with a 390 4V and a C6 with about 100K. One day on the highway, a motor mount let go and yanked the throttle open. He had to throw it into neutral to avoid wrecking and, of course, blew the engine. When they tore it down, besides the damage, the motor was as clean as a whistle with no sludge build up and no noticeable wear. The car had been in the family since new and they had always used Quaker State. I remember Quaker was getting a bad rap (no pun intended) even then, that lasts to this day. It doesn't reflect on today's Quaker, but at least in this 390, there were no issues with this oil.