Kay, that CAN happen, especially on older equipment. There are regulations now, that all new equipment must be e-10 compatible. Ethanol should not be a problem anymore. I know I have an old Stihl chainsaw that is 15, maybe 20 years old. I did have to replace the fuel lines, and the little diaphragm in the carb, one time. I remember the new parts having a sligtly different look to them, like they were made of different material, and have had zero issues since. Been running e-10 in it for as long as I had it. I also have an Echo trimmer that is well over 10 years old, that has countless HARD hours on it (I replaced the trimmer line with a carbide saw blade and put close to 100 hours a winter on it clearing brush and cedar trees), also with zero engine problems.
The 'problem' with ethanol, from what I remember from my shcooling on it, isn't so much the ethanol itself, as ethanol when it gets contaminated with water. For corrosion (and most forms of rot/decay) to form, there needs to be a presence of moisture. The problem is that ethanol can absorb enough moisture into itself, to allow it to be a catalyst for the corrosion/rot. Where I live, there are numerous ethanol plants nearby, and they actually haul a tanker less than 10 miles into town to fill the blender pump where I fill up at. I have never even heard of anyone having ethanol related problems there (well, except for one guy who hit the e-85 button and filled up his old farm truck with it, and barely made it home). I actually get equal or better MPG, in all my viechles, using e-10, over regular no-lead, and about equal mileage to the high-octane (used to be 'premium') no-lead, and at 30-40 cents a gallon cheaper. In our flex fuel van, we can go up to e-30 before we start losing MPGs.
In 2 cycle engines that use premix, ethanol contaminated with water, can lead to a whole bunch of other problems. Get 'enough' water in there, and you can ruin the engine. The problem being that ethanol mixes with water, better than oil. Let e-10 premix contaminated with water sit for long enough, and there will be a layer of ethanol/water at the bottom of the tank, with little to no oil in it. The ethanol has enough octane for the engine to run, but without oil, it won't run for too terribly long. It will keep the oil in suspension for a while, so always, ALWAYS, shake your premix cans, chainsaws, etc, to be sure that you don't have that separation issue with your fuel.
