Think of all the parts that 'Share' the oil. You have the engine, transmission and clutch all sharing the same filtered oil. Think about the needle bearings, roller bearings, ball bearings and plain bearings, all those precision surfaces that have to use this shared oil. Then there's the hydraulic tappets and you certainly don't want any impurities entering them and causing them not to work right.
I operate under the 2500 mile oil change rule, because of severe stop and go around town riding with some highway miles.
If the recommended oil change interval is 4000 miles that's long enough for any oil to remain in an engine.
I've often heard about Wing owners who have bikes that have gone over 100,000 miles and some 200,000 and that one thing is those owners take great care in the maintenance of their bikes and then I hear about an individual with an 1800 who has nothing but problems with the trans or engine (blames Honda for a shoddy product) and tries to avoid maintenance any chance they can.
Always follow the maintenance table in the service manual for good results and long vehicle life.
I.M.B.B.A. Technician II Certified