C'mon Doug, that's like staring a thread on what is the best penetrant, and I think you know the answer to that one
Back when there used to be small engine shops (remember those) every single one I've been in had a prominent sign stating not to use gas more than 30 days old. Regular gas, ethanol or not will degrade in about one month unless treated with something. Try to use Ethanol free gas ONLY, if you can get it where you live. Ethanol is murder for these small carbs. Hell my B Bodys all get better gas mileage with it, which offsets the extra cost.
I'll go against the grain on this one. I used to use STA BIL years ago but no more. SEAFOAM
for me in all of my small engines. The factory rep came in to my local NAPA and gave us the whole dog and pony show, how it's made from petroleum and it's good for fuel storage, adding to the oil, burning old top end fuel deposits etc. They say it'll preserve fuel for up to a year, I've been using since it for years with no
problems. Plus he gave me a bunch of cool stickers for my toolbox so it has to work, right? When I used Stabil back in the day it was hit or miss, had some fuel go bad in under a year more than a few times. Now whenever I store a car for the winter I add a can to the tank and have zero fuel related start up issues in the spring. Also all of my gas cans for the small engines (mowers, minibikes, trimmers and so on) get treated with Seafoam regardless if I'll use it right away or not. This way if I happen to leave gas in anything for an extended period I'm covered.
With all that said, even with the Seafoam if the fuel is a year or so old I don't chance it anymore. I just pump it out of the tank and dump it in my trusty Ranger. That thin will burn anything!