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Warning: How Quickly Does Gas Go Bad?

Wait. Really? Can gas actually go bad?

The short answer is yes.

With rising gas prices, it may be tempting to make the gas in your tanks (or gas can) last as long as possible. But this isn’t the best choice. It’s also easy to underestimate how long that full gas can has been sitting in your garage.

Today, we’re looking at whether you should use up your extra fuel or if it’ll be safe to use the next time you need to use it.

Let’s get started!

Does Gas Really Go Bad?

Gas does go bad. How long it takes to go bad depends on a few different circumstances. The type of gasoline will play a factor in its lifespan. However, heat, oxygen, and humidity also significantly contribute to the longevity of your gasoline. 

The gasoline you place in standard metal or plastic containers will begin to degrade and lose its combustibility after several months. If you’re using gasoline with an ethanol blend, it will degrade in a couple of months. 

This means if you use a seasonal gas can for RVing, lawn care, or generator backup fuel, it can likely go bad.

You can drastically increase the longevity of the fuel by mixing in a fuel stabilizer. This can help your gasoline last upwards of a year or two before it shows any signs of degradation.

It’s a good idea to add a fuel stabilizer to your gas tanks if you know the fuel will be sitting for quite some time. It helps ensure your gasoline is ready to go the next time you need to use it.

Pro Tip: Need to fuel up? We found an essential app you should download now! Check it out: GasBuddy App: Why Every RV Camper Needs It.

How Can You Tell If Gas Is Bad?

Much like milk, you can tell if your gas is bad by looking at it and smelling it. If you’re using it in machinery, you may even notice that the equipment runs rough, stalls, and possibly see check engine lights on your instrument panel.

If so, these are clear indications that the fuel you’re using is not good. Cease using this fuel, and it’s a good idea to siphon out the old fuel from your equipment.

How Quickly Does Gas Go Bad?

How quickly gas goes bad depends on where and how you’re storing it. Gasoline stored in hot environments or a container that’s not entirely sealed can begin to degrade in a matter of months.

This is why you want to ensure that you’re storing your gasoline in a completely sealed container and not in a humid or hot environment.

If you have gasoline left over at the end of the season, invest in a fuel stabilizer additive. Stabilizers help your gas stay fresh, so it’s ready for you months later. Failure to do so can result in damage to whatever equipment you fill up next season with the old gasoline.

What Does Old Gas Look Like?

Old gasoline will tend to have a muddier look than fresh gasoline. Good gasoline is relatively clear but can have a greenish or even a slightly bluish color to it. Gasoline darkens as it ages and eventually turns to a deep amber color.

If you’re questioning the quality of your gasoline, unscrew the cap and peek inside. If you notice it looking darker, it’s a good idea to dispose of it safely. However, that’s not the only test you can do to test your gas.

Old gas canister stored in shed.
Be careful when disposing of old gasoline to properly dump it with hazardous waste.

What Does Old Gas Smell Like?

Gasoline also has a very distinct smell. When gasoline ages, it loses its distinctive odor and becomes somewhat sour. Many feel it has the look and smell of varnish, which typically isn’t all that appealing. 

Smelling the difference between good gasoline and old gasoline is relatively easy. When in doubt, it’s best to play it safe and replace old fuel with fresh fuel to avoid any issues. It’s not worth damaging your gas-powered equipment.

Pro Tip: If you’ve spilled gasoline on your clothes before, you know it can leave a long lasting odor. We uncovered How to Get Gas Smell Off of You and Your Clothes.

Is Two-Year-Old Gasoline Still Good?

Gasoline, if left untreated, begins to experience degradation after a few months. If you’ve had gasoline sitting around for a couple of years, it’s best to dispose of it and get new gas.

Reach out to your local hazardous waste center to verify how to properly and safely dispose of old gasoline.

You can damage engines and other components by using old gas. Saving a few bucks using old gas is not worth replacing a lawnmower, car, or other gasoline-powered devices. 

What Do I Do With Old Gas? 

Gasoline is incredibly dangerous, and it’s crucial that you safely dispose of it. Most cities or counties have disposal facilities to handle hazardous chemicals like gasoline. Dumping old gas on the ground is incredibly dangerous and harmful to the environment.

Contact your local hazardous waste center and ask them about the proper way to dispose of your old gas. You may need to bring it in an approved container or on a particular day of the week, but it can help you to know you’re disposing of it in a safe and environmentally-friendly way.

Have you ever had to deal with old gas?

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  1. M Bruce Parker says:

    Mixed ethanol & gasoline degrades faster than just gasoline. Non-ethanol premium is available in many states. Some states have non-oxy other grades. [ND: regular] [WI: mid-grade.] That said, fuel stabilizers like Stabil are worth the effort if you store fuel for longer than months.