We have written many times about how using ethanol (alcohol, aka moonshine) as a gas additive is a scam, and nothing more than a massive farm subsidy which is raising the cost of food.
But I just learned more. When you use gas with ethanol, it can destroy your gas-powered power tools and mowers. I just had a conversation with my local Stihl and Scag dealer yesterday - my Stihl hedge trimmer needed a new carburetor. Guy said the ethanol kills these machines - their lines, their carburetors, etc. He says it's also murder on outboard engines.
He explained that it's less of a problem for pros who use their tools daily, but if you use your tools occasionally, the alcohol - being water-soluble - separates from the gas and makes a mess. The new carburetor cost me $97.
His advice: Run the machine down to empty if you aren't going to use it for a while, and always use fresh gas - don't use two-month-old gas.
If you are like me, you have five gallon containers of vintage gas-oil mix left over from last fall. Get rid of it, somehow.
Here's one article on the subject.