I mix a small can of gas(1 gallon)at 16 to 1 oil mix with about 4 ounces of Sea Foam in the mix. I fill the tank full and run it until I see the heavier oil smoke. Shut them off and don't touch them until spring. Then I dump the fuel out and refill with the correct lower oil ratio called for. I do this on my string trimmer, leaf blower, and boom saw. Since I started doing this 5-6 years ago I have not had any issues at all.
In my chainsaws and cut off saw I run Sea Foam in then year round. They may set for a day or a month between uses. I have not had problems since I started using the Sea Foam.
I also try to get gas without ethanol in it.