I have heard of people changing to synthetic fluid and having leaks and some having no leaks. I am not sure how many miles were on the trannys in question.

If the fluid is so bad that it is thicker than it should be, then it should be changed. Flushing just gets all the fluid out of the tranny. This is normally not possible because some remains in the passages and valve body. Some MB transmissions even have a drain plug on the torque convertor so that can be drained. Getting all of the old fluid out of the tranny is a good thing.

There is alot of bad information out there about automatic trannys. I think the tranny shops want everyone to be afraid of them. Search some of the posts on this forum to see different peoples experiences.

__________________
Doug

1987 300TD x 3
2005 E320CDI