The transmission service is best done at a dealer, in my opinion. It takes a special MB certified fluid that is outrageously expensive. The service on my 1998 E300 TurboDiesel cost me about $260, and most of the price was the fluid. So because of the fluid being unique and the fill process reqiring the fluid level be checked hot, and the fact that the car doesn't come with a dipstick for the transmission fluid level, it becomes a dealer job. The dealer will tell you the transmission is "sealed for life and never needs a fluid change" and then you have to ask him what "life" is, and then direct him to change the fluid. I think today MB will voluntarily change the fluid, but three or four years ago they put up a fight. They now know better, I believe. I change it every 60,000 miles. It is coming up on time for another transmission oil change. Jim

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Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)