Old gas in tank what to do

When gas gets old, it loses some of the combustibility it needs to fire up an engine. Because gas is flammable, though, getting rid of it is a little complicated. Here's what you need to know.

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From powering vehicles and generators to garden tools, gasoline makes our world go around. But unused remnants of the fuel that have been stored too long in your garage or have sat in the gas tank of your riding lawn mower all winter can degrade or become contaminated. At this point, you need to deal with it through legal disposal or through reuse after dilution with fresh gasoline. Disposing of gas illegally or inappropriately—for instance, pouring it onto land, into storm drains, or down toilets—can incur fines, damage the landscape, kill animals, contaminate water sources, and even pose a serious fire risk.

Read on to learn how to dispose of gasoline safely and responsibly.

STEP 1: Inspect the gas to determine whether it is contaminated or just old. 

To find out whether gas is old or contaminated, pour some in a glass container. Pour a little fresh gasoline in another container for comparison.

If the questionable gas is darker or smells more “sour” than it does like fresh gasoline, it has probably aged to the point of losing efficacy. Storing gasoline for more than a few months (and for who knows how long in the gas station’s tank, before that) causes it to degrade and lose combustibility, which can ultimately inhibit its ability to fire your engine. While old gasoline won’t hurt an engine, it will either make it run inefficiently or may fail to fire the engine at all. You can certainly dispose of old gas altogether, but you may also be able to use it by diluting it with fresh gas (see Step 2).

If, however, the leftover gasoline shows particles of rust or dirt, or if it’s cloudy or discolored, it may be contaminated. Do not reuse this fuel. Instead, skip to Step 3 to dispose of it, because those particles can clog fuel lines and carburetors.

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STEP 2: If you discover that you have old gasoline rather than contaminated gas, use it by diluting it with fresh gas.

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Old gas has lost some of the potency that would have enabled it to fire an engine. Still, you can usually use it up by diluting it with newer gas in the tank of a vehicle or outdoor power tool. When mixed in the right proportions, the old gas will lower an entire gas tank’s combustion ability by so little that it’s not much of a concern.

• If there’s a half tank or less of old gasoline in your lawn mower, filling the rest up with fresh gasoline might dilute it enough to get the engine firing. You’ll burn through it pretty quickly as you work in your yard, so you may want to top it up with more fresh gas midway through the chore to get a little more oomph from the fuel.
• Larger quantities of gas can be diluted in your car or truck’s gas tank. First, check your vehicle owner’s manual or look online for its tank capacity, which should ranges from about 9 gallons to 16 gallons. For a small tank of 9 or 10 gallons that reads at least ¾ full according to the fuel gauge, add a half-gallon of old gas to the tank. Use a proper “jerry can” (a gas jug with pouring spout) to slowly pour the old gas into the tank. Eyeball the gas level as you fill it, and stop when the tank is filled to just below the tank mouth’s safety flap. (That metal flap gets pushed into the tank mouth when you insert the gas nozzle; it’s designed to prevent gas from spilling into the area between the tank mouth and the gas cap so you don’t get rude surprises when you take the cap off.) Similarly, you can add ¾ of a gallon of old gas to a nearly full 12-gallon tank, or a full gallon to a 16-gallon tank.

If you’re adding old gas to fresh gas in a vehicle, you may also want to ask employees at your local automotive supply shop whether using fuel additives would allow you to use less new gas in your tank, and thus use up your supply of old gas more quickly. Fuel injector cleaners are often useful in getting rid of old gasoline, depending on the engine in question and the kind of fuel involved. Ask the auto pros whether fuel additives or other additives might be useful in your situation. (CarBibles’ review of the best fuel injector cleaners is a helpful resource, too.)

Of course, you can always just choose to dispose of the old gasoline instead. Disposing of it is a good idea if the fuel is a dark rust-brown or chocolate color, which may signal the presence of deposits or impurities in your engine.

STEP 3: Research the nearest hazardous waste and gasoline disposal sites for old or contaminated gasoline.

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There are four main ways to discover where to dispose of old gas in your area. These disposal facilities tend to have limited hours, so be sure to note when they are open for dropoffs.

• Search online for “hazardous waste disposal center” in your county, city, or state.
• Call your county or city waste management agency and ask where to dispose of gasoline safely.
• Check with your local fire department. Given gasoline’s flammability, these fire experts usually have good ideas about how to handle old gas and where to take it if you have to get rid of it.
• Ask your auto repair shop to take the gasoline off your hands. Many will not because they may have to pay a fee to deal with it on your behalf, but if you’ve already got a great relationship with an auto repair shop, it’s worth asking. (Or offer to pay the fee yourself!)

STEP 4: Transfer gasoline to a government-certified container.

Using a funnel, carefully transfer the old or contaminated gasoline from its existing container into one that is government-certified specifically to hold gasoline, such as a jerry can or plastic gas jug. Many fire codes require that containers store a maximum of 5 gallons each. (You can find these containers at home centers, automotive stores, or gas stations.)

Pour gasoline into the can slowly to avoid splashing, static, and spillage, and fill no more than 95 percent of the way to leave room for the fumes. Keep your face as far away from the spout as possible to minimize gas inhalation. After you’ve finished pouring, tightly seal the container to prevent spills or leaks.

If you’ll be driving the gas to a location for disposal, place the container upright in a second receptacle, such as a cooler or bin, to catch any spills if it should topple over or suffer a leak. Then wash your hands thoroughly, in case any gas has splashed on you.

STEP 5: Clean up any gasoline spills.

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If any gas has gotten on your clothing, change your clothes and address the stain and odor promptly. First, you’ll want to blot the excess off with a white cloth. Cover the affected area with baking soda to absorb whatever the cloth cannot. Let it sit for a few minutes, then brush it clean. Finally, rub liquid dish soap into the stain to treat it, let it sit for about 5 minutes, and then launder the clothes by themselves in the hottest water the fabric can withstand. Line dry, and don’t put the clothes into a dryer again until you’re sure all traces of gasoline have been completely removed. Lingering gasoline can trigger combustion in a hot dryer.

If you spilled gasoline on the driveway, soak up as much of the fuel as possible with an absorbent product, such as kitty litter. It may take a few hours to absorb the spill, then sweep up the litter and dispose of it. You can take care of any remaining stains with our driveway cleaning tips.

RELATED: How to Get Rid of Gas Smell

STEP 6: Transport the gasoline to a disposal center.

While transporting gas, drive carefully and never, ever smoke in the vehicle. Fumes could be lingering or gas may have splashed on you, and it takes very little gasoline to combust with open flames in a small space.

Once you reach the disposal center, you should be able to empty your gasoline into their storage vessel. Take the empty 5-gallon jug home so you’ll be ready the next time you need to dispose of gasoline responsibly.

How to Handle Old Gasoline Safely

Gasoline is highly toxic and flammable. Be sure to take every precaution when transferring and disposing of it:

• Always work outdoors when handling gasoline because it’s dangerous when inhaled. If you can’t handle gasoline outdoors, get indoors ASAP if you notice a burning in your lungs.
• Call Poison Control immediately at 1-800-222-1222 if you swallow gas by accident. Drink milk right away, too, and await further instructions.
• If you get gasoline on your skin or in your eyes, flush it out with cool water for at least 15 minutes. If after this time the gas continues to bother you, seek medical attention.

Final Thoughts 

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Gasoline that has been stored too long can degrade or become contaminated. While it is possible to use up gas that has deteriorated, it’s usually best to dispose of it and buy a fresh supply.

Keep in mind that gasoline must be disposed of carefully It’s illegal to simply leave it at the curb or dump it down a storm drain. To make sure you’re handling your old gas properly, check your local waste disposal regulations. Municipalities often have special disposal sites or hazardous waste collection events where you can take old gasoline.

Although it’s important to know how to dispose of old gas properly, it’s better not to have to deal with it in the first place. To keep leftover gas to a minimum, buy only as much as you need, use it promptly and, at the end of the season, be sure you use up any fuel left in your gas-powered outdoor tools.

FAQs 

While this article has covered the basics of disposing of or using up old gasoline, there’s certainly more to say on the topic. Read on for answers to a few of the most common questions about getting rid of old gas.

Q. Where can I dispose of old gasoline?

Never dispose of old gasoline with your regular garbage or recycling. Contact your county or city waste management department to find your closest hazardous waste disposal site or to learn about special collection events near you. Note that you’ll need to transport the gas to the site in an approved container.

Q. Is 2-year-old gas still good?

Without fuel stabilizer, 2 years is too long for gas to sit, whether it is in your car or in a container. Ethanol gasoline in a car’s gas tank lasts at most 3 months before it starts to evaporate or degrade; ethanol-free gas can last up to 6 months. A fuel stabilizer can push the lifespan of ethanol gasoline up to a year or so and stretch the life of non-ethanol gas even more.

Q. Can you dilute old gas with new gas?

While old gas that’s contaminated should be disposed of, very small amounts of uncontaminated old gas can be used up by diluting it with fresh gas. Be sure to use a just a little bit of old gas in proportion to new. For instance, in a ¾ full tank that holds 9 or 10 gallons, use no more than ½ gallon of old gas. In a ¾ full tank that holds 16 or more gallons, you should be able to use up a full gallon of old gas.

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