I have a 2007 Yamaha YZ450F, as far as I know it's never been rebuilt or anything, but it's never been raced. When I got it, it had the original white anniversary edition plastics and stickers. I decided to do an oil change after realizing the oil level was low when I got it, and now I have less than 6 hours on the oil and it's not even hitting the dipstick. That seems a little excessive if you ask me, but there is no smoke or leaks coming from the bike at all. The compression is still there also. I have no problem rebuilding it, I just don't want to rebuild it if it doesn't need it. I just don't understand where the oil is going.