91 sl500, auto, 110k on car. transmission having major slips, hard sifts, rmps almost 2k more at 60. reverse had a painfully hard time catching.

I had a expedition with this problem , not as severe tho. found a fluid that claimed to restore surfaces to a certain extent. did great work on the ford.

Any one know of this? I have a strong feeling the trans is gone, Cosio off of lois. "my mechanic" said his wifes sl300 had close to the same problems then one day just died.
We pulled all the oil out, refilled with the proper amount. seemed to help for a few days.

 

The tranny is 18 years old, so it's probably on it's way out.
Bring it to the dealer and have them diagnose it.
If it's the tranny get a used one and have your mechanic replace it.