How many miles do you have on the car? It is a 2000 E320 correct? Is it stilll under warrantee?
I thought I read in the Mercedes Club magazine that Mercedes has sealed the transmission and if you open it it voids the warantee. Please check with Mercedes before doing this.
Mercedes found that 90% of transmission problems were improper servicing. the felt it would be better if they could just keep untrained mechanics out of them they would lst longer.
But of course it is your car, Do as you please. I would hate to have you void your warrantee by doing this.
Of course youmay be way over the warrentee.
Dave

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1970 220D, owned 1980-1990
1980 240D, owned 1990-1992
1982 300TD, owned 1992-1993
1986 300SDL, owned 1993-2004
1999 E300, owned 1999-2003
1982 300TD, 213,880mi, owned since Nov 18, 1991- Aug 4, 2010 SOLD
1988 560SL, 100,000mi, owned since 1995
1965 Mustang Fastback Mileage Unknown(My sons)
1983 240D, 176,000mi (My daughers) owned since 2004
2007 Honda Accord EX-L I4 auto, the new daily driver
1985 300D 264,000mi Son's new daily driver.(sold)
2008 Hyundai Tiberon. Daughters new car