when you buy a used turbo, then most of the time the seals WONT be in very good condition...not being used is as bad or worse than running them to death.....if you're turbo's seals are going bad, then you'll usually find oil somewhere between the intake outlet and the head.....usually, you will get blue exhaust smoke too....sometimes, when it's bad enough, it will leak from the housing itself after shutoff.......not that many parts to a turbo....when a turbo isn't allowed to cool down properly(not using a turbo timer) then the oil burns and builds up on the shaft.....eventually, something has to give...it might take 50K miles to prematurely wear it out, or it might take a few miles.....