Change the oil often (most of our scooters don't have oil filters). These scooters require very little oil so it cannot be a cost factor, only a hassle factor. As most scoots are air cooled the oil breaks down more quickly than in an engine that is water cooled. If the scooter is new, run it for at least 1,500 miles, changing the oil twice as often as the manual says during this time. (The piston rings will need to "set"). After this "break in" period start using full synthetic oil. If the spark plug appears to foul (sometimes happens), then switch to a blended synthetic oil. Yes, synthetic oil is by far the best lubricant you can find.