FWIW, I change oil every 2500-3000 miles. Standard Rotella 15w-40 in my DOHC. My SOHC noticeably preferred 20w-50.Much smoother shifting/clutch action/neutral findability (making up words is fun
). My DOHC does have an oil cooler of a 900 which probably helps.
But I only change the filter every other oil change. Personal choice. Probably not endorsed by the FSM.