As far as Mobil 1........ Hands down 1 of the BEST oils available today.
Motorcycle specific oil not only doesn't have friction modifiers, it's also non-detergent oil, both of which can cause damage to a wet clutch. But, I was told by a Brit bike mechanic, that because the older RE's have cast iron cylinders they tend to run hot, breaking down oil prematurely. And that by running a good synthetic car motor oil with friction modifiers it can help increase the life of the motor without damage to the wet clutch because the clutch is in the primary case with a separate source of oil.
Personally, I think I'm going to start running 10W-40 Mobil 1 synthetic and add some BG MOA. THAT, my friends, is amazing stuff.