Not sure, but my uncles 85 22R was worse. Had a around 160K miles on it, he like never changed the oil. I did it for him once, and the thing came out as black and nasty as the tar pits. But the thing still ran awesome despite the dirty air filter, old rotor/cap and wires with electrical tape on them and different lenghts hahaha....it went to show me just how darn tough these things are.