OK water is the chief enemy of your fuels ability to function in your engine. The alcohol in our fuel is
hygroscopic or something like that and I probably even misspelled it but all that means is the tendency for the alcohol to suck water vapor right out of the air. Everytime the fuel can is opened a new load of air (with its water vapor) is allowed in. So in reality the life span is of your fuel can is not predicated so much on age but in the number of can openings along with the relative humidity of the air at the time of those openings.

I have also used some very aged fuel with good success as well as seen some fuel only months old become useless. So what Terrellflyer said is really good advice just "use it till it won,t run". When you got some like that don,t dump it this is great for cleaning engines and soaking frozen engines in. Another good use for that fuel is in a separate bottle for the times your nose takes a header in the dirt its great hosing off the engine and grime away from the venturi.

John