Thanks for the information, but my realy question is why FSS can not reset itself after a fresh oil change? It should find out that the oil quality has changed so much that it should be good for another 10,000 miles. ANyway, I was just confused when I did an oil change on my ML with 3500 miles. I checked FSS and it indicated exactly the same number of miles before and after the oil change. And after driving a tank long, the FSS continued to decrease the number (7000->6700 or so).