I haven't yet switched either of the Benzes to synthetic ATF but will be doing so at the next scheduled service. I have read on the Ritter/Easley list that it works out well, especially in cold weather areas where trans performance is compromised until the fluid is warm. I used synthetics (both Redline and Mobil 1) extensively when I used to live in Colorado and noticed significant improvement, especially during sub-zero start-ups in the high country, but better shifting in warm weather too. In fact, Redline 75-90 transformed a manual trans in an Audi quattro from being a candidate for replacement to quiet, smooth and slick shifting. Redline MTL is what the BMW guys use to get their cars' manual transmissions to shift as they should.
'76 Moto Guzzi 850 Le Mans