I got really obsessed with this topic a while back, and I did a long term fuel test. I tried to replicate the conditions that caused the fuel problems in stored equipment.....like log splitters, generators, leaf blowers, chainsaws, snow blowers, tillers...all the equipment that goes for periods of time without being used. In the old days the carbs would gum up when the fuel went bad - with E10 the carbs become badly corroded and some of the rubber parts dissolve.
The end result is that I found the untreated E10 can begin the phase separation in as little as 50 days.....and that all fuels will eventually go bad (Avgas is the exception).
http://suzukisavage.com/cgi-bin/YaBB.pl?num=1382699778 I believe it is better to store unused equipment empty, and when my summer equipment is no longer needed, the fuel is drained and the engine is run until the carb is out of fuel. I have also started to use Sta-Bil fogging oil in the engine to protect the cylinder from corrosion over the winter, and protect the cylinder for the first startup in the spring. The method is the same for the winter equipment - but they are just now coming out of storage (log splitter, chainsaws). My generator has a small amount of Avgas in the tank - but the fuel valve is closed and the carb is empty.......I can start it up by turning on the fuel valve and letting the Avgas run to the carb, and then add E10 pump gas for extended operation (the E10 will be removed again before storage). I realize this is a somewhat labor intensive chore to drain out the fuel - but I no longer have to remove the carbs and clean them to get the equipment running again.
For my 2 cycle equipment I mix up the fuel in 1 gallon batches, and use it up regularly. If the equipment is not going to be used for an extended period....the fuel comes out of the tank and the engine is idled until it runs out of fuel.