While we're at this thread, it may be worth a point to mention that the rear axle oil (which uses tranny oil too) needs to be changed. This is most often overlooked for some reasons or other.
All our MBZs changed the rear axle oil recently and it runs smoother and quieter. Perhaps it was peace of mind that all is well at the rear.
126 tailed by a 203, 129 leading the pack.