Still, toro and several others have ethanol documents on what happens. Ethanol is a very aggressive 110 octane solvent more than it is gas. It takes 21 days in average Michigan weather to degrade from 91 to 86 octane. Longer in winter. Humidity plays a big role and only perfectly sealed metal containers can prolong ethanol life. As ethanol was originally designed to attract water from gasoline, similar to dry gas. Since it's also a great desiccant , the more humidity the faster ethanol degrades and wants to turn back to its plant like state.
Unfortunately here in MI the only place you can get non ethanol is Marinas , where boats on the water are considered a life critical use, and they can't afford to have failures and strand people on the water. Thus NO damaging ethanol sold at marinas for boats. Alaska is the same way, but the whole state is considered life critical to have dependable fuel.
Any of these new pro saws should have the motomix or stihl fuel, it's not worth the risk of one bad fill up. There are plenty of brand new farm boss and similar on craigslist for sale that are only slightly used. But seized. Every 10% ethanol leans out the ratio 3%.
Lucky with drag race tracks nearby, we have easy access to VP or Turbo Blue. Often they will sell cheap the last few gallons of a 55 gallon drum, and if stored properly that race gas will last MANY years, as long as it's not the oxygenated nitro fuels. It doesn't take much of C16 to blend with pump gas to be plenty safe, just mix for an octane of 94-100 range. Any higher and the saw doesn't have the compression to take advantage of the high test.
Most importantly real gas and race gas smells way better than nassty ethanol junk.