[Jeff H]

I used Mobil 1 synthetic in my old supercharged 93 Z28 Indy 500 Pace Car. Car ran great with 74K miles on it and a little over 40K with the supercharger. Right now I run Castrol Syntec in my SS454 pickup and it's the cleanest looking oil I've ever seen in an engine after 5K miles. But then my engine is also only 7.9 to 1 compression so that may contribute to it looking so good. If your car has ever sat through hot, cold, and humid conditions in the garage, then I would bet there's some moisture buildup inside the engine. If you don't get a chance to run the engine for a good 20-30 minute drive every other month then I would change it after 6 months or longer if it has been sitting. It's cheap insurance against a rebuild.