What type of transmission fluid does a 1999 Mercedes 430 use? on 1999 Mercedes-Benz CLK430

My trans fluid leaks when the car sits for more than a week or 2. Now I drive it more frequently and it's beginning to leak while i'm driving. It seems to be leaking from the top which I was told was a breather or vent valve. What could cause that and what type of fluid can I refill in the meantime?

Asked by for the 1999 Mercedes-Benz CLK430
it probably is a electrohydraulic control unit connector leak (13 pole ) ,get it fixed ,these transmission are very dependable and is not worth the risk of dirt getting inside of it ,use only Mercedes Benz ATF