I just got a used M5 with 8Ks on it. It is in excellent condition, and I'm pretty certain that it has been taken care of. The very first thing you should check is the clutch. If not broken in correctly, the clutch will be pretty messed up. Drive it around a little. (hint: go test drive a brand new M5 if possible, I did before purchasing my used M5) Another thing to look out for is the date that it is delivered since there's been some debates on oil consumption on the message board.