With automotive engines, the Achilles heel, in terms of oil formulation, is the flat tappet cam. ZnDDP-free oil will result in wiping a cam flat. But, flat tappet cams went bye-bye 35 years ago. In a vintage engine with a conventional flat-tappet cam, Rotella is way better than contemporary oil formulations...especially if stiff valve springs and high-velocity lobe profiles are used. But, Rotella is marginal at best, in terms of zinc & phosphorous and it's a diesel oil. The vintage car crowd has been getting mixed results from Rotella, in the last couple of years.
These engines are very different from automotive engines. The rely on flow volume, not pressure, and the clutch + tranny share crankcase oil. That's a harsh environment and a lot of different oiling requirements. Contaminated clutch discs are not horrible to replace, still a pain. It's the shift forks that are the Achilles heel of these engines. More times than not...far more...shift forks are burned and in need of replacement. Of all repairs, that's the most time-consuming & messy, once an engine is assembled and running.
You could buy ZnDDP additive, then add it to get back that safety margin. However, Honda GN4, Valvoline & Castrol bike oils, JASO-spec, are proven safe choices. Considering the huge .8L crankcase oil fill capacity, how many quarts of oil is anyone going to run through one of the bikes in a year? IMO, doesn't seem worth the effort to save a buck a quart.
As for fuel, ethanol-free is best, if you can find it. Once exposed to ethanol, rubber parts swell...then shrink and turn brittle, if allowed to dry. They will bounce back, after a few days of fuel re-exposure...sometimes. Other times, the petcock packing washer must be replaced. These engine will run fine on E10, once the carb has been tweaked to compensate. Unless you source something like "tru fuel" or specialty "storage fuel", which is pricey, no fuel has much of a storage life any more. Even the E0, corn syrup-free flavors contain oxygenates. Thus the entire fuel system should be drained and dry for storage.
In terms of octane requirement, Honda specified minimum 86. No problem running anything from 87-octane pump regular to 93 octane "premium". Static CR is only 8.8:1.
