Just to add to Benzmac's response, I have a 1987 300E with 170k and it had the guides replaced relatively early in her life, and the seals have been replaced twice, the last time being about 5k ago probably. This fixed the oil problem both times, so don't worry about it much, just get the valve guide seals replaced, ran me about 120 bucks. Hope this helps. Oh Benzmac, I am moving to Atl so you will have a new customer by the summer's end.
Chris