High mileage vehicles may develop a leak from one or more of the transmission oil seals.Google+
Car Problem Reports
Mercedes-Benz E320 Transmission Oil Seals May Leak on High Mileage Vehicles
Mercedes-Benz E320 Problem
Average Mileage: 177,500 mi (50,000 mi - 249,500 mi)
Visitor, 2000 Mercedes-Benz E320, 180,000 mi
Leak around seal
Visitor, 2000 Mercedes-Benz E320, 170,000 mi
Shortly after purshasing the car (had 150k at time of purchase) I had to have a transmission valve replaced. Within a month the trans quit entirely. About 9 months later the new (refurbished) trans is leaking fluid. I have to put a qt or so in every month or two, about $16 a qt.
Visitor, 1999 Mercedes-Benz E320, 195,000 mi
Severe leaking of transmission fluid, not easily diagnosed, and definitely not a cheap fix!
Visitor, 2001 Mercedes-Benz E320, 200,000 mi
seal leaked, no dip stick, supposed to be a maintainence free system. tranny fried.