I have a 1982 300SD Turbodiesel that I have done a substantial amount of work on since getting (2 years ago). I have noticed oil on the air filter the last 2 oil changes. I know on my last car, a Mercury, that was bad and ended up quickly having the engine gone. My 300SD has over 200,000 miles on it and I'm concerned and want to make an informed decision on engine condition to decide whether to keep the car or bag it and get another. I live in the DC area and the car has started fine in the cold weather and seems to run just fine. Any thoughts or tests I should run? I assume a compression test, but what numbers would indicate good/bad on the engine? Any other tests? Thanks for the help...