transmission slipping after fluid change
 

My friend has a 1997 E420 with 145,000 on it. He had the transmission fluid & filter changed and within 2 weeks the tranny started slipping. The mechanic did not change the torque convertor fluid. It did not slip before. The replacement fluid was the expensive M/B fluid for the 722.6 transmission.

Did the mechanic cause the tranny to start slipping because he did or didn't do something he should have? Any opinions would help.

If a service is done on a 722.6 that has really nasty fluid, its not unheard of for the trans to go tits up once the new clean fluid has been run in it for a short bit. Assuming that there are no leaks and the trans is full of fluid, I wouldn't immediately suspect tech incompetence. It's a rather straight forward trans to perform a service on.

FWIW, there are stories of normal running 722.6 trannies with a history of Mercedes spec 236.10, and then slipping after a fluid change with the newer spec Mercedes 236.14 fluid. Mercedes sez baloney, car should be fine with 236.14. Fluid 236.10 seems harder to find but I recently saw some at NAPA and they said it is readily available. IIRC it was Febi or some other German brand name. It is also possible that the tranny will adapt to the new fluid and run fine after awhile.

That's what I was told by my mechanic, when I had the fluid changed in the transmission of my w124, it started not shifting and was acting as though it was going out. But a few weeks later it was back to normal 100%. I would say it just needs some time to adjust.