I changed out whatever ancient oil was in the CL-100 (probably 20 year old Pennzoil) and put in Rotella T5 10W-30. That's what I run in my small engines. One thing I noticed; it used to be that the clutch would stick if the bike had been sitting for any length of time, apparently from squeezing the wet clutch between the pressure plates. Before starting the engine, you would have to put it in first, squeeze the clutch, and rock back and forth several times before the clutch would unstick. If you didn't do this first, you would get a uncomfortable lurch when you put it in gear, and I'm sure that's hard on the the gearbox. Now it seems it doesn't stick nearly as bad. I barely moved it and boom, clutch is unstuck. I'm guessing this a good thing, yes? Clutch feels fine and it's not slipping.