I've never run any additive in any of my bikes, going back to the late 1960's. As long as the motor oil meets modern JASO MA specs for use with wet clutches, and viscosity requirements as indicated by the bike's manufacturer, it should be good as it comes out of the bottle.
The main thing to consider with using modern motor oils in bikes with wet clutches is to avoid the "energy saving" or "resource conserving" automotive oils that contain friction modifiers that can negatively affect wet clutches. These are usually 10w-30 and below, although we've seen reports of at least one 10w-40 motor oil that has the "resource conserving" mark on the label.
slmjim & Z1BEBE
A biker looks at your engine and chrome.
A Rider looks at your odometer and tags.
Bad idea. Keep in mind that the clutch is bathed in motor oil, so any additives may negatively effect the clutch plates. Just be sure the motor oil you use is marked "JASO-MA" and you'll be ok. JASO-MA is the standard for motor oil in engines with wet clutches. Ed