Don't know if it's unrelated, but I put Mobil 1 synthetic ATF in the tranny of my '91 190e 2.3 about a year ago at 165k hoping it would help the harsh 1-2 shift, but it didn't.. Now my tranny is starting to flare/slip going from 2-3.

I have since switched back to conventional, so I personally wouldn't reccomend it