Okay, my warranty is up on my 2002 Buick Century (3.1 only available engine) and I will now be changing my own oil instead of taking it in for service. I t has had Pennzoil the past 36,000 miles and I have no complaints. Basically I am thinking of either sticking with the Pennzoil or buying Chevron Supreme from my local TSC. Although retail priced the Chevron is generally cheaper, it is easy to find Pennzoil on sale at enough places that the cost difference is nill. Any opinions on one oil vs. the other, I really don't think I can go wrong with either. Any thoughts would be appreciated. Thanks!