[QUOTE=pkor;2163457]
When I drained the original oil, by the way, it came out clear. So I would not rush to change that oil, unless you know exactly what to put in. /QUOTE]
Remember that a tranny is not an engine, so the oil will stay clear unless you had something major league wrong happen to the gearbox. I won't claim to be a tribologist, but after many years/miles/temp changes I would expect the oil to deteriorate and to pick up particles.
As far as the right oil, the MBUSA list says ATF is OK for manual trannies except models GL76/30-5 and GL275E. There is also a part nr for manual transmission oil A000 989 26 03, but I don't know any more about it.
There was a big discussion in the thread below that basically said Redline's MTL (not MTL90) was good:
http://www.peachparts.com/shopforum/showthread.php?t=62660&page=2