I have a 1985 Honda Shadow with 60,000 miles on it. The bike runs great and everything works fine. I have run Rotella 0-40 and 15-40. The motor runs the same with both- no usage and comes out very clean. I find the shifting to be a bit notchy and seems to be worst with the synthetic in it. The clutch feels better with the 15-40 so that is what I am running. The shifting is getting worst and I only have about 1500 miles on this run of dino. My question -- is there a better oil that will not shear down as fast in this shared sump design? What about a 20-50? Any comments would be appreciated. Thanks Roger