(Updated on April 20, 2022)
Keeping an extra canister of gas is handy for car emergencies or for gas-powered garden tools, but it’s sure to become an annoyance if it’s forgotten and left too long; old gas doesn’t burn well.
Gasoline is made up of several compounds, some of which are known carcinogens and highly toxic to animals, people, and the environment. It’s explosive and highly flammable in both its liquid and vapor form. So unsurprisingly, the disposal of gasoline is carefully regulated and controlled.
The best practice is prevention; it’s best to use your stored gasoline regularly so it doesn’t go bad. Avoid storing it through the winter if your power tools are also in hibernation at that time.
If you find a questionable container or some of your engines aren’t firing well, you can inspect the gasoline at home before seeking out a disposal service.
Safe Gasoline Storage
It’s very important to keep gasoline in a specialized fuel storage container. Never fill it to the brim. You want to leave some air at the top to allow room for some expansion (though fuel containers should have a vent to avoid overpressurization, this is intended to be a backup safety feature).
Never mix gasoline with other compounds, even if you intend to dispose of it later. Incompatible liquids can cause a dangerous chemical reaction. Mixing chemicals could prevent disposal agencies from safely accepting the fuel waste.
Keep the gasoline on the ground to avoid the extra pressure that can build when containers are placed on a shelf in closed places that can get very warm (such as garages and sheds). Warm air rises.
Never store gasoline in the trunk of a vehicle, in a basement, or near a furnace or other flame. Water heaters often have a pilot light that may ignite fuel vapors.
Follow any other directions on the can of gasoline to prevent damage, fires, and serious injury or death.
How Long Will Gasoline Last?
Proper approved gasoline storage containers have special vents to keep water out and allow vapors to leave so that the containers don’t become dangerously pressurized. In one of these, gasoline should last about six months.
If a gasoline stabilizing product has been added before storage, the fuel can last up to 12 months.
Inspecting Old Gasoline for Potential Repurposing
Before throwing out or using any old fuel, perform a visual inspection by carefully swirling your gas canister to mix it and then decanting some into a clear glass jar. It’s best to compare it to a bit of new fuel in another jar so that you know how it should appear.
Check the color: new gas is light-colored, old gas is darker. The darker the fuel, the more it’s oxidized and the less it will burn.
Check for sediment at the bottom and for the presence of water. New gas should have little to no sediment.
Take a small sniff: old gas can either smell unusual, not at all, or very strongly of varnish.
If there are no abnormalities then the old gas can be used in a small motor such as a lawnmower, weed whacker, or snowblower, as long as it’s mixed with at least 50% of new gas. For the most purity, strain it with a paint filter first.
Can I Run Old Gas in my Car?
Once your gas starts to age, it won’t burn as well. This can cause issues with your car’s engine, such as knocking or misfires.
In severe cases, your car may have trouble starting at all, or start and then immediately die.
Can You Dump Old Gas on the Ground?
Never dump old gas on the ground, no matter how convenient it may be. It will eventually find its way into the water supply of animals and people, and will damage vegetation and wildlife on the way. This practice is also illegal in most places.
Can You Pour Old Gas Down a Drain?
For the same reasons, never pour old gasoline down a drain. It can also damage the pipes.
How To PROPERLY Get Rid of Old Gasoline
The best way to get rid of old, unusable gasoline is to check with the local government, fire department, or waste disposal services (i.e. the dump).
Call and ask if there is any regular pickup or drop-off for gasoline, or if there are certain hazardous waste disposal events. Hazardous waste disposal events typically occur on a regular interval, such as once a month or once a year.
You can also search online (Earth911.com is a good website) for “household hazardous waste” disposal in your zip code to find local collection or recycling events.
Before packing up to go, call the facility first. It’s important to know the type of container the gasoline must be in, the cost for disposal, the hours of the service, and if they accept cash and/or card. The fuel container may not be returned to you after the fuel is discarded.
Does AutoZone (or Other Store) Take Old Gas?
Most major auto parts stores don’t take old gasoline, though they often take used motor oil.
Can You Simply Let Old Gasoline Evaporate?
In the past, some people have poured old gas into a flat dish and set it outside to evaporate as a means of disposal. If you do this, it will leave behind an oily residue that is still hazardous.
Letting gasoline evaporate still isn’t a good idea since the toxic fumes are released into the environment. Check with your local laws to see if this practice is legal in your area.
If you choose to do this, be careful where you set the pan of gasoline as the fumes are very dangerous in a closed space (both a combustion risk and hazardous if inhaled).
Can You Throw Gas Cans Away?
Gas cans can often be thrown into the trash if they are completely empty, but the regulations for this depend on the state and county. Check with the local waste collection services first.
Note: “Completely empty” does not mean rinsed with water. Rinsing the container would put gasoline into the water system and is not necessary for this means of disposal.