I like the Chevron oil that I am using right now, but I am considering using Schaeffer's Oil. What do you think of Schaeffer's Oil? What are the zinc levels in Schaeffer's-not high enough to cause cat converter problems? I own a Saturn SL2. I was thinking about going to 6000 mile oil changes, with a K&N Oil Filter and 3 oz. of Auto-RX in the oil. The Saturn is one of the cars, along with some Toyota cars, vans, and maybe trucks and SUVs, that are supposed to be kind of sludge monsters. How will Schaeffer's Oil do in a Saturn?