Originally Posted By: car54
5w-40 or 20w-50 oils produce the same results in my scooter. After extended long distance riding, the 20W-50 keeps the valves noticeably quieter, so that's what I run.
Mine is an aircooled vino 125, so not apples to apples, but I have seen ruckii with over 20,000 miles run on whatever oil was cheapest at the time. It sounds like yours will see very little use, but you are concerned with a top notch oil.. maybe look into valvoline VR1 synthetic 10w-30? Probably 10x the oil quality at a similar price to GN4, and the same viscosity should allow you to enjoy all 3.5 horsepower to the fullest.
I ended up using some Valvoline VR1 synthetic 10w-30. I wanted to drain the factory oil and the dealer was closed today so I went to Auto Zone. It was the only 10w-30 that wasnt listed as energy conserving (which the manual states not to use for whatever reason). The oil states that it is high in Zinc. Whats the purpose of zinc? It says racing oil on the bottle (its NOT the version of VR1 that isnt street legal BTW).