Had gasket replaced by a local shop 3 times. It is still leaking. Is there a trick to this or could it be some other problem? The last time it was there they replaced it with a gasket from Mercedes.

 

Are you sure it is not the transmission connector socket that is leaking? This is a common problem and costs very little to fix, the O-rings in it fail and leak oil. It is a round yellow object, just above the pan, with wires coming out of it. It is on the passenger side.
Failing that get another shop to look at it.

 

I second that.

Purchase one of these and have your shop install it. Maybe they will do it for free since they have misdiagnosed it 3 times....

https://www.google.com/search?q=2035...hrome&ie=UTF-8

 

I find sometimes people go to their mechanic and 'tell' then what is leaking/needs to be done. OP was unclear except saying he had his mechanic replace the pan gasket. Now we all know if it is the connector leaking, said mechanic should have seen/known this (after the first return for same problem 'leak') but yes, the mechanic should replace the connector for free (customer supplied parts).

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