For the lowest cost of ownership and reliability -that Onan needs to be run under a moderate to full load at least monthly. Running the unit like this will keep moisture out of the oil, keep the generator end slip rings from corroding, and keep your carb from gumming up. I am a strong believer in ethanol free fuel for small engines. If you have to use ethanol fuel -stabilize it to prevent phase shifting(fuel component separating) and the related corrosion that happens from this condition. I always keep my fuel tank full and the fuel treated with a mixture of Stabil and SeaFoam. Startron is also a good product.