I use an old fashioned "squeeze bulb" style siphon on my ZNEN-50 scooter every 2500 miles or so, then let my mechanic do a $50 "full service" every 10000 miles (oil change, battery check, tire check, wires, plugs, cvt clean and check etc.).
Mind you, I could only get away with that on a 50cc motor with 0.75 pint oil capacity and a wire strainer instead of a filter...