I have a Honda EU3000i generator as well. Just before we had an auto standby generator installed, we lost power for about a day. With the Honda, I powered 3 freezers, a fridge, and the TV. It used a little less than 3/4 tank of gas
I use Seafoam, 2 oz per gallon for 2 cycle engines, 1 oz for 4 cycles. I don't drain out gas for the winter. I have never had any problems, but has is never around for more than 8 months. It's cheaper than buying non ethanol fuel.
Key point. If rad inlet hose is hot, check the air temp coming out of the fan (watch fingers). If there is a "goodly" amount of heat coming out, the coolant is flowing properly. If no heat out of back of fan with rad inlet hose hot, then there is low or no flow.