Hi,
I looked into replacing my supercharger oil in my C230K, and I came up with the same solution that it was never meant to be changed, like Swozza said, if it has lost any during work, there is a filler I believe but no drain (C230K W202), also from what I can remember the oil has to very accuratly measured as if to much is put in it can cause foaming, I decided to leave mine well alone till I ever had a need to remove it then I could drain and refill it easily.