I do know that the early M103 motors were notorious for valve guides and seals needing early replacement. However, I still hear of it needing to be done on late M103 motors also.
This has spurred me to ask about my M104 motor in my 1995 C280. What is the average for guides/or/seals replacement? I now have 122k miles on mine, and I burn, on average, at most a quart of oil in 4-5k oil changes. Though there have been times where I noticed I needed probably 2 quarts between an oil change. Though I do drive hard, and do a lot of freeway driving with high revs, so I know that makes it more likely to burn oil.
My question, what wears the seals/stems faster, TIME or MILEAGE? I drive about 30k a year. Car still runs and performs like a champ... I am VERY good about oil changes, and other maintenance, but I do really drive this baby hard. What would one assume a good time to take off the head and/or do the seals or guides? Think I'd be good for 200k miles with my good maintenance, albeit a lead foot.