Mercedes approved only two types of ATF fluid for power-steering use: Dextron Type II and Type "F".

Most ATF fluid today is Dextron Type III which contain slipperiness additives, which is why they will eventually leak if you continue to use a Dextron Type III ATF fluid in your power-steering unit.

I myself just purchase MB's powersteering fluid, and no worries.

:-) neil
1988 360TE AMG
1993 500E