Take a phenomenally reliable Honda 350cc air cooled single cylinder motor. Brand new, never fired. New clutch with heavy duty springs. New billet cam, hard welded rockers, and heavy duty valve springs. The motor was intended for offroad use, and originally came with a simple oil cooler. It is now going into an onroad application, and it now has a proper finned oil cooler. I am unaware of the original maintenance schedule for the motor. Ignoring the initial break in period (it has to be done a certain way in this situation) what sort of interval would you use? Usage will be 6000ish rpm cruising with minimal in town usage.