I just change my trans fluid the other day on my 1988 560sl
I used I used Penzoil Working fine
The thing is to make sure you drain the convertor
Also rotate the engine in the correct clockwise direction
or you can mess up the timing chain
I moved mine with a large screw driver from underneath the car to get the drain in sight
there are holes by the flywheel ring gear, but be careful on the teeth
Replace the filter and clean the pan and make sure it is clean
The trans and covertor took 8.2qts. of fluid
Make sure you put 4qts in first then run it through the gears before adding the last 4.2 qts.