In my own experience, this has not proven true. There might be others that have different experiences, but I assure you this is the absolute truth.
I have been using 87 octane 10% ethanol in every gasoline engine I use for decades.
- 2012 90hp Evinrude Etec outboard purchased new
- 2011 Cub Cadet 50" riding lawn mower purchased new
- Push lawn mower given to me by my mother some 30 years ago
- Montgomery Wards garden tiller that I purchased used about 30 years ago
- Jiffy ice auger purchased new about 20 years ago
- Stihl 028 chainsaw I purchased new in 1985 and used professionally for 5 years
I keep the mixed fuel for my chainsaw in an old anti-freeze bottle and because I don't use the saw very much anymore, it can get to be a couple years old, but it has always worked when I needed it.
I maybe use my push mower two or three times a year and any gasoline left over is left in the tank over the winter. Same is true with my garden tiller which is used maybe once per year.
When I park my riding lawn mower in the fall, I just leave whatever gasoline is in the tank sit until the next year. Starts right up every spring.
In all those years, I've only experienced gasoline going bad one time. It was in the fall one year with an old Ice King ice auger I got from my step father. I'm guessing it was a 1970's vintage. One fall before freeze-up, I pulled out my ice auger and tried to start it to be sure everything was good to go. When it wouldn't start, I opened the tank, and the gasoline smelled like diesel fuel. I drained it out, replaced it, pressed the primer about 5 times as usual, and started the auger. That was about 25 years ago.
I will say this. Never had a problem so the only reason for this is probably just a habit since it was required by the manufacturer to maintain my warranty for the first five years, but every fall when I winterize my boat motor before winter, I do put a fuel conditioner/stabilizer in the tank. That motor is now 12 years old and has never failed me.
The only other thing I do and again this is just a habit that I picked up over the years, is that I do add a carb/injector cleaner to a tank of fuel probably once every year or every other year. I have experienced improved fuel economy and performance in my truck by doing this.
Here's something else. Ethanol does not cause water to accumulate in the fuel. That is a myth that has been going around for years. In fact, it is actually beneficial to help prevent fuel line freeze-up and is one of the alcohols used in fuel system antifreeze along with methyl alcohol and isopropyl alcohol. The water can accumulate even in a tank with no ethanol as it comes from condensation that forms in the tank from temperature and humidity fluctuations.