How do change the transmission fluid on a c270?

Answer 1

First step jack the car up to a nice height, fit axle stands on either side to support the car, once done use the appropriate socket to open the nut on the gearbox sump, let the oil drain.

Once the oil has drained, undo the small nuts around the sump pan, then drop the sump pan down, then remove the transmission filter, on some Mercs these are a simple slot in filter, and some models the might be 2-3 retaining screws.

Once filter is removed clean the bottom side on the gearbox and also clean the sump pan, best way for this is a small paint brush and a bit of petrol, fitting the filter and sump is the reversal of removal.

When everything is back in place, fill the Transmission Fluid where the dipstick would actually go, fill in 2 litres first, run the car so the gearbox oil warms up, the oil level needs to be checked when the car is running.

3-4 litres will be more than sufficient unless you bleeding the torq converter, the gearbox oil needs to be blood red in colour and should be suitable for automatic transmissions, AQ3 is a good synthetic oil for merc gearboxes.

The dipstick to check the transmission oil level can be purchased at the dealer or better option would be on ebay, C270 cdi runs an 722.6 gearbox which is shared with the E class models also.