This is the politically correct answer to "what to do with 27 year old gas?" and I think it's also the right answer. Sometimes the PC answer is right.
Call your city and find out if they have a household hazardous waste collection center or if the county does. Most do, nowadays. Take the gas to them. Unfortunately, they may want the containers, so find out beforehand and use whatever is handy (old paint thinner cans or cat litter jugs) and put the gas in that. With 27 gallons, you may have to make a few trips. I know it's a hassle but it is the correct thing to do. The gas will probably be fuel blended and used for cement kiln fuel or blast furnace fuel depending on what part of the country you live in. Good luck.
