Disposing of old gasoline?

When we started the restoration on the 72 it had just about a full tank. 3 years later I have 3 5 gallon gas cans with 3 year old brown gas in them that I use for cleanning parts, the concrete floor, my hands, anything. It also saved me when I first got my 73 dart and found out that the fuel gauge is off by about an 1/4 of a tank and I was late for work. I filtered some into a can with an old shirt and it got me out the driveway and to the gas station.