I changed my oil at 1000 and again at 2500 miles without resetting the computer... My car is now at 5200 miles and the FSS says 2800 ... I don't believe the computer can guage the breakdown of the oil. I believe it is just a clocking mechanism used to remind you of routine maintenance.

PS: At 2500 miles I had my mechanic pull the oil pan and clean it before replacing the oil... Most engines will shed bits of metal during the break-in...

The next time I take it in for oil, (in the next 1k miles) I will also have the mech change my tranny fluid and rear diff. oil...