This is an evergreen topic, that eventually polarizes folks. It's also more important than ever, since automotive oil has been reformulated in a way that delivers the worst possible combination of properties for these engines.
Honda GN4 is good oil, if a tad pricey. Take it FWIW, I've run it exclusively for the past two decades with excellent results...22K miles on the motor (Honda Nice 110, in the interest of full disclosure) and nary the slightest sign of fatigue. It's still wearing the factory valve lash settings. That said, is it the "best"? ...highly debatable. Is it the only oil anyone should ever use in one of these engines?...no. There are other excellent oils out there that are wet-clutch compatible, meet current JASO specs and have adequate zinc to protect the tranny (especially the shift forks). Castrol, Valvoline, Spectro, AMSoil, Motul and others all sell this type of oil. I am unabashedly old-school...translation, stick with what works unless & until there's an overwhelming reason to change.
At less than a quart per oil change, how many quarts are you ever going to use in one year? That's key, because the best oil (within the required specs) is clean oil. For a bike that sees few miles annually, you're better off changing oil every couple hundred miles, or so, after break-in. For a high-mileage road bike, 400-mile intervals are getting near the upper end; I go by color. When the oil starts getting a suntan, time to change it. The other important part of engine maintenance is cleaning the oil spinner, inside the clutch face. After break-in, it should be cleaned every 1K miles or at the end of the riding season (annually) whichever comes first. Prior to offseason storage, the oil should be completely drained, while hot, & the spinner cleaned...that'll prevent sludge from ever forming. The oil screen can be cleaned, it never needs to be replaced. It's there to catch big stuff...boats, old tires, etc:34:
