I have had a '91 K75SA since November of 2003. It had 20,763 miles on it when I bought it, and now has 28,004. No trouble whatsoever. It is fully up to date on service, and I had the clutch splines lubed ahead of the specified miles due to the age of the bike.
I just got back from a ride to New Orleans and back (to New Hampshire): 3,560 miles.I did about half interstate (70+ mph) and half two lane (50 - 60 when not in towns). I noticed that I had used about 2/3ds to 3/4ths of a quart of oil. Is this in line with what others have experienced?
Also, the dealership will only recommend BMW oil, which I am using (synthetic), but I notice that the owners' manual does not even call for motorcycle specific oil. This makes sense to me, given the dry clutch. I looked at some other threads on this forum, and see people are using a variety of high quality non-motorcycle oils, but I didn't find anything specific to K75's. Any thoughts?