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How Long Gas Lasts (And How To Make It Last Longer)

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Gas lasts for up to six months before oxidation and degradation cause the gas to lose its combustibility as long as you store it properly. If gas is not stored correctly, it will only last a month before going bad. 

The rest of this article discusses how to store gas, different types of fuel, fuel stabilizers, and how to identify and dispose of bad gas. Keep reading for answers to your questions about gasoline expiration and storage. 

How Long Does Gas Last?

Garage corner with three red plastic fuel cans

Gas that is in a sealed container lasts up to six months. After six months, gasoline begins to oxidize and degrade, losing combustibility. Gas in a tank starts to go bad after one month.   

Gas can and does go bad, though there‘s no set rule or expiration date for gasoline. How long gas lasts can vary depending on whether or not it is appropriately stored, the time of year, and if you’re using a stabilizer. 

If gas is stored in a sealed container, it can last up to six months before going bad. However, gas in a tank will start degrading in just one month. If you’ve left gasoline in your lawnmower’s tank for a season, it is most likely bad, and you’ll need to dispose of it. 

Gasoline consists of carbon and hydrogen atoms which create combustive hydrocarbons when they bond together. These hydrocarbons are what powers engines to run. As time passes, oxygen molecules in the gasoline start to change the structure of the hydrocarbons in a process called oxidation. When hydrocarbons oxidize, they are not as combustible. 

Furthermore, the ethanol in your gasoline attracts water molecules in the air, diluting the gas and making it less effective. This process is similar to putting a bunch of ice in a beverage on a hot day – as the ice melts, it dilutes and waters down the drink. 

If gasoline is stored correctly, these processes slow down, but it is impossible to stop them completely. For that reason, gas will only last a maximum of six months. 

How To Store Gasoline To Make It Last Longer

Gasoline is highly flammable, so it can be hazardous if it isn’t stored correctly. Here are some guidelines for proper gasoline storage: 

  • Check your local and state laws about gasoline storage. Some local fire codes and city laws restrict how much gasoline an individual can store, so make sure to abide by these rules. Most homeowners cannot keep more than 25 gallons (113.65 L). You should also only store gas in containers that are five gallons or less. 
  • Store gas in an approved can. I recommend this gas can, available on Amazon because it comes with a button that allows you to control the flow of gasoline from the can when you’re ready to use it. Additionally, it is compliant with EPA and CARB restrictions. The flame mitigation technology makes it a safe choice. Ensure that any can you use is sealed tightly and that you handle it with care.
  • Don’t fill up the can all the way. You should leave some empty room in the can for expansion and prevent spillage. 
  • Don’t store gas in extreme weather conditions. Gas should be kept at room temperature and away from the sun or other heat sources, such as a space heater or furnace.
  • Use a Fuel Stabilizer. Fuel stabilizer will make your gasoline last longer. Keep reading to learn more about it!
  • Don’t smoke anywhere near stored gasoline. Gas is flammable, so you should avoid having any flame near it. 
  • Keep your gas can away from children and pets. You wouldn’t want your kid or animal to knock over the tank and cause a spill, so make sure it is in a place they don’t have access to. 
  • Do not store gas in your home. You should keep the gas can in your garage, or if you have a shed, that’s even better. The vapors are dangerous, and it is not worth the risk to have gas in your house. 

If you follow these guidelines, your gas will stay good and usable for six months. In general, though, the sooner you use it, the better.   

Safety Measures for Handling Gasoline

If you get gas on your skin while getting it in or out of the storage can, don’t panic. If you just get a little bit of gas on your skin and wash it off right away, you should be fine because the skin does not quickly absorb the chemicals in gasoline. Make sure you wash the skin that the gasoline touched thoroughly with warm water and soap.

If you’ve washed your skin and still notice the gas smell, mix some vanilla extract with water and rub it on your skin until the smell has gone away. Any vanilla extract will do, but I recommend this brand. It contains only all-natural ingredients, and it is made in the USA.   

If you do get a lot of gas on your skin for an extended period, you may notice the following symptoms: 

  • Skin irritation 
  • Cracking skin 
  • Blisters 
  • Peeling 
  • Discharge 
  • Burns 

If you notice any of these symptoms, you should get to a doctor right away. 

Different Types of Fuel and How Long They Last

There are four different types of fuel with varying lifespans. The following table outlines all the information you’ll need about these kinds: 

Type Characteristics Shelf Life 
Gasoline Fossil fuel made from petroleum.Typically available in three grades: 87 AKI, 88-90 AKI, and 90-AKI. Up to six months if stored properly, one month if in a tank, or up to two years if stored with a stabilizer. 
Diesel Made from petroleum, but through a different process than gasoline. Used for large and industrial trucks. Diesel vehicles typically get better mileage than gas cars.More expensive than gas.  Up to twelve months if stored properly, up to two years if stored with a stabilizer. 
Ethanol Added to gasoline. Some car manufacturers are making vehicles that can be powered by ethanol alone. Ethanol or gasoline blended with ethanol can only last three months because ethanol oxidizes quickly. 
Bio-Diesel Created with vegetable oils or animal fats. Used to fuel compression-ignition engines.Shelf life of up to six months if stored in a sealed opaque container. 

Knowing the type of fuel your vehicle needs and that fuel’s shelf life is an essential part of being a knowledgeable and safe vehicle owner and driver.

Bio Diesel in a Beaker in a Lab
Biodiesel

What Is a Fuel Stabilizer?

Fuel stabilizer is a mix of antioxidants and lubricants that bond with gas to prevent evaporation and extend the shelf life of fuel. Most stabilizers can extend the shelf life of a fuel by a year. 

If you plan on storing fuel for longer than six months, or if you have seasonal equipment such as a lawnmower or a boat, using a fuel stabilizer is essential. In general, you should add one ounce of stabilizer per three to five gallons, but you should consult the instructions for your specific stabilizer. 

The Best Fuel Stabilizers

The following table provides recommendations for fuel stabilizers and discusses their pros and cons. All products are available on Amazon.com. 

Stabilizer Pros Cons 
STA-BIL Storage Fuel Stabilizer Claims to keep fuel in good condition for two years. Works for all gas engines. Prevents varnish buildup. Tests well Recommended by multiple manufacturers. Made in the USA. More expensive than other fuel stabilizers. Their formula is a secret.
STAR BRITE Star Tron Enzyme Fuel Treatment SEF Gasoline Formula Claims to protect fuel for two years. Tests well Works for diesel and gasoline. Works with two and four-cycle engines. Helps engines run smoothly. Improves fuel economy. Higher initial cost Multiple reviewers said their product arrived leaking.
Royal Purple Max Clean Fuel System Cleaner and Stabilizer Improves fuel economy. Increases horsepower. Reduces engine knocking and pinging. Versatile Not scientifically verified. Not as widely tested as other products. 

Getting a high-quality fuel stabilizer is essential if you want to store your fuel for longer than six months. Otherwise, your fuel will go bad. 

How To Tell if Gas Is Bad

Now that you know gas expires, you may be wondering how to tell if the gas in your tank has gone bad. Here are some symptoms of bad gas: 

  • You’re having difficulty starting your car. Gas that has gone bad does not provide enough power to start the engine, so if you’re having problems starting your car, this could be a sign that your gas has gone bad. However, there are many other reasons why your car may be struggling to start, so this isn’t a sure sign of gas expiry. 
  • You’ve noticed reduced fuel efficiency. If you see that you’re going through gas more quickly than usual, your gas may be bad. You should also get your fuel tank checked if you notice this issue. 
  • Your car is sputtering when it is idling or driving. If gas has gone bad, it doesn’t combust evenly, which causes your engine to sputter. 
  • Your car isn’t accelerating well. Accelerating requires a burst in power, which requires more combustion and more gas. If your gas is of bad quality or expired, your ability to accelerate will decline. 
  • The check engine light is on. Of course, the check engine light is ambiguous, so the check engine light being on could mean many other things. However, if the light is on and you’re experiencing these other symptoms, your gas may be bad. 
  • Your car changes speed without you pressing the pedal. Because bad gas doesn’t combust evenly, you may notice abrupt changes in speed without you touching the gas pedal. 

If your gas is bad, you need to dispose of it safely. 

How To Dispose of Gas

Old rusty jerrycans

If your gas has gone bad, you need to dispose of it. Because gas is corrosive and flammable, you can’t just dump it anywhere. Gasoline needs to be disposed of properly. It is illegal to dispose of your gasoline without following proper procedures. 

The procedure you need to follow in disposing of gasoline depends on where you live. Different towns and cities have various requirements and protocols. Typically, the process looks like this: 

  1. Put the gas in a container intended for fuel and make sure it is airtight. Set your container in a bin to prevent it from tipping over while driving.  
  2. Find a waste disposal site near you and call them to see their hours and rules. Some sites have limited hours, so it is always best to call ahead to save time and effort.  
  3. Drop it off according to the site’s rules. Be sure to check with an attendant and place the gasoline in a safe waste disposal area. 

You can contact your local recycling center or your city government to locate a disposal location. Some hazardous waste disposal centers charge a fee for disposal or have specific hours, so it is essential to do research ahead of time. 

Some places also have a maximum amount they’ll accept from a single visit or individual, so make sure you abide by those rules. 

You may need to pay for private disposal. You can find a private disposal business by searching for “private hazardous waste disposal” and your city. Make sure that the company you choose is licensed. These services can be expensive, but sometimes it is your only option, especially if you have a lot of gasoline you need to get rid of. 

Some cities have recycling and disposal events that encourage their citizens to dispose of waste responsibly. Contact your local government to see if they plan on holding any of these events anytime soon. 

Some fire departments are willing to dispose of gasoline for you. It is worth contacting them and asking if this is an option. Even if they don’t dispose of the gas for you, they will probably offer suggestions for disposal centers. 

Most importantly, do not just throw away gas in a trash can or pour it down any drain. Irresponsible disposal endangers public health. Furthermore, if you illegally dispose of your gas and authorities find out, the penalty can be hefty fines or even jail time. 

Conclusion 

If you haven’t driven your car or used your lawnmower in a while or are looking to stockpile some gasoline, you must know about gas expiration. In general, gasoline appropriately stored in a sealed container can last up to six months, and any gas in a tank starts to go wrong after just one month. Any attempt to use bad gasoline is unlikely to go well, so it is essential to track how old your gas is.

For more, check out How Long Does Gasoline Last? | A Fuel Storage Guide.

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