I just bought my wife a Kymco People 150cc scooter. It is air cooled and has no oil filter just the screen. It calls for 15w40 oil and I would like some recommendations on what would be a good oil in this motor. She is just going to be riding it around town and it winds out at about 65mph. I am running Amsoil 20w50 in my twin cam 88 and really happy with that. I plan on at least once a year change intervals and probably twice a year if she rides it much. It holds less than a quart which is why I think this application warrants a good synthetic with short change intervals.