when do I need to do a transmission service. my MB GL 450 has 35K ?

thanks a lot

your welcome.a little info about checking your transmission fluid,below. Transmission Fluid Level Check Mercedes-Benz GL450 (2007-2012) Our research indicates that your vehicle does not have a transmission fluid dipstick. These types of transmissions are designed to be maintenance free. In order to check the transmission fluid, your vehicle likely has check valve on the bottom of the transmission on the bottom of your car. Your car must be level when the fluid is checked and we therefore recommend having a mechanic with a hydraulic lift or underground bay check your transmission fluid. Any fluid leaks for this type of transmission should be treated by a mechanic