After a long search, I found a lubricant that's right between grease and oil. It's actually quite runny, but still adheres well. I have a good feeling about it. See the following link: (Unfortunately, the stuff is almost as expensive as gold or diesel! ;-) )...
I also had to open my motor because of a slipping freewheel bearing. Here's a tip for anyone else: I cut a roughly 1mm deep groove on the seam between the brass and aluminum using a lathe. After that, I was able to loosen the brass part with heat and then glued it back in place with a bit of...