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How to Dispose of Old Gas?

  • Car Care Tips
  • Celine Jerly
  • 8 minutes

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Gasoline ready to go in the garbage? It’s good you’re here before tossing it out – fuel can be a serious health, safety, and environmental risk without proper storage and disposal. So, handle it with care even though you can’t use it anymore – here’s how to dispose of old gas safely. 

Yes, gasoline has an expiration date, and usually, it’s as short as 3-6 months. So, you’ll not be dealing with old gas disposal if you buy just enough to power a frequently used car or equipment. You could make it last longer with proper storage and additives – however, do not expect years of shelf life. Whether sitting in a gas can or a vehicle left unused for long periods, petroleum-based fuel oxidizes, breaks down and gets contaminated over time. Decomposition and impurities in gas will cause serious damage to engines or affect their performance. It also becomes a fire and environmental hazard if you do not know how to dispose of old gas safely.  

So, let’s find out what happens to old gasoline. When should you get rid of it, and how? 

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See: Car Super App Way.com and Shell Offer Savings on Gas

How to check if the gas is old? 

You can identify old stale gas easily by checking the smell or color. Here’s how to do it: 

Look Test: Check if there are visible contaminants like rust or dirt. Foreign particles in gasoline settle at the bottom – you’ll see a dark layer of sediments if the gasoline is contaminated from corrosion or exposure. It’s best not to use the fuel even after filtering it, as fine particles from the grit remain and could eventually clog the fuel system.  

Color Test: Gasoline is clear, almost colorless, but you’ll notice a faint amber hue. If it’s any color other than that or cloudy, it’s time to dispose of the old gas. As it oxidizes, the fuel becomes darker with an orangish hue, eventually turning brown as it breaks down and decomposes. If left to spoil for longer, gasoline will look cloudy with impurities.  

Smell Test: Most people know what gasoline smells like – yup, the one you catch a whiff of at the gas station. So, take a quick sniff (not a full breath) and see if the old gas smells different. Don’t expose yourself to the fumes for too long. If you can smell a musty, sour scent like stale lacquer or a dingy basement, it’s off – find out how to dispose of the old gas.  

Will old gas evaporate? 

Gasoline is mostly hydrocarbons from refined crude oil. The fuel is mixed with chemicals that keep it stable and inhibit corrosion. However, there is a limit to these additives’ effect, and once they wear off, gasoline will start evaporating and oxidizing. Eventually, what is left becomes a sludge that clogs up engine fuel systems. 


How does gasoline go bad? 

Over time, oxidization and evaporation turn gasoline into a sludgy varnish like old lacquer. Even if the consistency hasn’t changed and the color looks good, it could be contaminated by dirt or rust from the tank. When you use the old gas, these contaminants or the leftover sludge gets into a carburetor, fuel injectors, or filters – gumming up the engine and damaging it. So, it’s best to remove it from the tank and figure out how to safely dispose of the old gas.  

You must be wondering how it decomposes – blame it on water and alcohol. Fluctuations in temperatures cause condensation inside fuel tanks or storage cans. So, if not from direct exposure, water gets into gasoline from moisture in the air. As the fuel absorbs more water, it forces out the alcohol from gasoline. Separated alcohol and water sit at the bottom of the tank or gas can. So, instead of inhibiting corrosion, the alcohol additive spoils the fuel and, potentially, engine parts too. Water contamination could also lead to fungus/bacteria growth.  

Storage cans and cars are not the only places gasoline can go bad. Keep an eye on seasonally or occasionally used equipment like chainsaws, boat motors, ATVs, etc. 

How long does it take for old gas to go bad? 

Considering all types of gasoline, the range is between three months to three years. But the limited shelf life extension is only possible with stabilizing additives and proper storage. You can’t leave your car or gas-powered equipment out for months and expect the gas to stay fresh. Dispose of old gas as soon as possible. 

Pure gasoline – the petroleum-based fuel without ethanol – can last up to six months as it doesn’t absorb as much water as other types of gas. There’s less risk of moisture contamination, and without alcohol, there won’t be sediments at the bottom – unless dirt, rust, and other foreign particles get in.  

The regular gas you use to fill up your car from gas stations has ethanol; typically, 10%. The alcohol in gasoline prevents corrosion. But it also mixes with water/moisture and reduces the quality of gasoline over time. So, regular gas lasts about three months or less. Keep in mind the fuel’s stored at the gas station for some time before you buy it – so factor that in when determining how old it is.  

If you don’t want to dispose of old gas frequently, stop buying more than you need or get shelf-stable gas.  

How to make gasoline last longer? 

Proper storage is the most important step in extending shelf life – even if you have self-stable gas. Store gasoline only in suitable containers – new plastic fuel cans are the best choice. Avoid metal cans; they can rust and contaminate the gas. Glass containers are unsafe, as the risk of breaking and being a fire hazard is higher.  

Pick a dry and cool storage location, preferably away from a valuable property like your home. Exposure to fluctuating temperatures speeds up evaporation and condensation – and you’ll have to dispose of the old gas frequently. If you are worried about seasonally used equipment or recreational vehicles, adding a fuel stabilizer can help new gasoline last up to a year or more. Stabilizing additives slow the breakdown of hydrocarbons and minimize water absorption, but they can’t fix old gas that’s already contaminated.  

See: Water-proof Your Car Gas Tank with These Treatments!

Can you recycle old gas? 

You could filter and clean gas to reduce contamination and reuse it for smaller engines. It’s best not to add new gas to dilute old fuel in your car – even after filtering, water content and other impurities can damage the engine.  

Use a fuel dryer like isopropanol and an octane booster to reduce water contamination. Combine reconditioned fuel with fresh gasoline in a 1:5 ratio. If there is rust and other debris, use a coffee filter or thin cloth layers to filter the fuel. However, if other fluids like antifreeze contaminate the gasoline, do not reuse and dispose of it responsibly.  

Also see: Is It Safe to Mix Ethanol and Non-ethanol Gas in a Car?


See: How to Siphon Gas: A Beginner Friendly Guide

How to dispose of old gas? 

Every state has a department in charge of environmental protection, and they set guidelines on how to dispose of hazardous waste like old gasoline. The rules vary from state to state and even city to city but must follow necessary safety regulations. Typically, you’ll need to take the stale gasoline to a hazardous waste-disposal facility. A quick online search for your city’s or state’s environmental protection agency website will help you learn more. If you cannot find a website, call your city hall, and they’ll guide you to the concerned authorities or a recycling coordinator.  

Meanwhile, here are some things you MUST NOT DO when disposing of old gas: 

  • Do not dispose of old gas in your trash or pour it down the sink/toilet 
  • Do not leave it out to evaporate; fumes from gasoline can be toxic and fatal 
  • Disposing of old gas in landfills is dangerous as it is a fire hazard 
  • Do not try to burn off the old gas 


Big cities usually have a hazardous waste collection schedule; toxic waste like gasoline is collected a few times a year at no cost to you. Waste-removal events are also common. But if you don’t want to wait till the next collection date, carefully transport the old gas to a commercial recycler or waste-disposal service. You’ll have to pay them a fee to dispose of or recycle your contaminated gasoline.

 Also See: How To Get Gas Smell Off Your Hands

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