Got a question for you, folks. How often do you really need to change the oil in your scoot? After the 600 mile service, what mileage should your next oil change be? I believe the 900 manual states 7500 miles (not sure because I don't have it in front of me as I type this) but I've heard some folks say there should be a change at 3500-4000 miles. Any thoughts/opinions?