Re: Where do you dispose of old gasoline?
If the gas is non-oxygenated (would say "for offroad use only" at the pump), it will last for quite some time. 5 months is a long time for gas with ethanol in it(all gas is typically 10% or more ethanol these days) The issue is that when ethanol breaks down, it gums up carburators. that being said, I would not put it in your lawnmower, weed wacker etc, unless you want to risk disassembling/cleaning the carb. It might be okay diluted in your fuel injected car's 20 gallon tank, but is it worth saving the $10 worth of gas if it clogs up your injectors?
For those of you that have been doing this for 30-40 years, the gas you buy today is not the same as it was even 10 years ago. I used to manage a hardware store a few years ago, and people were constantly bringing in lawnmowers/snowblowers that wouldn't start because they had old ethanol gas in them. Holiday gas is probably the worst of them all.