I run 100% gas in all my small engines. The gen is made to run on that ethanol blend, but ethanol still breaks down and makes a mess, so I try to not do it and if I do I run it completly out then add 100% back in for even short storage.
You can get quality gas, racing fuel, at a motorcycle shop. They sell it in steel buckets, and in a steel container the gas will store for a lot longer than a plastic container. It is high octane, and easier to get that AV fuel as its just on the shelf at a motorcycle shop.
I dont bother. I dont need that extra boost as I am not racing... lol