It has been decided here in the UK for Mercedes-Benz owners, the following, (AUTOMATIC MERCEDES ONLY)
Mercedes specialists in the UK, have come together on a Mercedes forum, and we have decided that the Automatic Transmission Fluid SHOULD be changed, and that it should NOT be sealed for life.
If your car has not had its ATF fluid & filter changed and has done over 40,000 miles, I reccomend that it gets changed now!
It will not need changing for another 100,000 miles afterwards.
If your car has done over 40,000 miles, please get it done ASAP, as it can cause transmission problems.
Mercedes-Benz UK decided on the more recent Mercedes (From 2006) that the Transmission Fluid and Filter gets changed on the 3rd service or approximately 37000 miles.
Please ensure your Mercedes has this done at some point!