Okay, I haven't weighed in on an oil thread in some time, but here goes.
1. Using motorcycle specific oil has nothing to do with the engine or the clutch. It's all about the transmission. You wouldn't use 10W/40 or 20W/50 in a standard transmission in a car, would you? No. You'd use 80W or 90W. But we're required use the 10/20 weights because it's all one case.
2. Early synthetics (first- weren't really "synthetic", just modified petroleum oils) had a bad reputation because the modification process left them physically thinner, and would leak out of older engines. Todays synthetice are lightyears ahead of them, and on par with the petro oils as well.
I have been using the Honda blend (HP4) WITH the Molybdenum since it came out in the mid 80s. I have never had to replace a clutch. Every bike that has come into my possession has experienced smoother shifting upon switching to this oil. And in one case, this oil solved a sticky clutch issue I had with a CB125S.
One thing. You can't use the Moly oil in anything that has an automatic (centrifugal) clutch.
