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How Long Can Gasoline Sit In a Car?

There are lots of reasons why you might leave gas sitting in your vehicle’s gas tank for an extended period. Perhaps you are leaving your car on vacation. Or maybe, you have a luxury vehicle you only take out for a drive once every few months. 


Whatever the case, you may be wondering how long can gas sit in a car. And if gas has a shelf life, just how long does gas last? Get these answers and more here. 


How Long Does Gas Last? It Depends

So how long does gas last? How long can gas sit in a car? Gasoline can last between three months and three years depending on the type of gas and if it is properly stored. 


It’s important to note while all gas will naturally begin to degrade over time thanks to exposure to oxygen (also known as oxidation), all gas is not created equal. Most gasoline sold at a standard gas station can last up to three months, but other types of gas can last longer. 


Learn more about the shelf life of three common types of gasoline below.


Pure Gasoline: Up to 6 Months 

Pure gasoline that is petroleum-based without any ethanol will typically last up to six months before it begins to degrade from oxidation rapidly. Pure gasoline doesn’t absorb water like other types of gas, which means it’s easier for this gas to avoid moisture contamination.


Ethanol-Blended Gas: Up to 3 Months 

“Regular gas,” meaning most gasoline sold at gas stations around the country is ethanol-based gas, which is typically 90 percent petroleum and 10 percent ethanol. This type of gas has a shorter shelf life than pure gasoline and typically only lasts for up to three months. Unlike pure gasoline, ethanol-based gas easily absorbs moisture, which can lead to contamination. 


Unfortunately, it’s nearly impossible to tell how old the gas is when you fill up your car at a gas station. This is because, from the time the gas reaches the gas station to the time you fill up your vehicle, it may already be a few days or a few weeks old. By the time you pump your gas, the gasoline could have sat at the gas station for over a month. So if you’re wondering how long can gas sit in a car, the answer is most likely up to three months from the time you fueled up at a gas station. 


Shelf-Stable Gas: Up to 3 Year

The type of gasoline that has the most extended shelf life is shelf-stable gas. Fuel stabilizers are available for purchase online and at local hardware stores and are petroleum-based additives that can be added to gasoline before storing it in your garage. Fuel stabilizers slow the oxidation of gas, making it last longer.

New gasoline fills a tank on a car of someone wondering how long gas can sit in a car.

What Happens If I Put Old Gas In My Car?

Now that you know how long gas lasts, what happens if you put old gas in your car?


The good news is that gas may already be a few days or a few weeks old, thanks to transportation time between six months and a year old won’t harm your car’s engine. Still, it can decrease your car’s overall performance, and you may notice adverse effects like poorer gas mileage than usual. 


However, gas that’s over a year old can cause things like engine knocking, sputtering, and clogged injectors. It’s rare to purchase gas at a gas station that is this old, but if you have old gas sitting around your garage that you’re considering using in your vehicle, we recommend correctly disposing of the old gas instead.


How to Identify Old Gas

Wondering how to identify old gas? For starters, when gas ages, the chemical properties of the gas start to change. If you have old gas that is in your car, you may experience the “check engine” light turning on. Old gas can burn improperly, which can trigger your check engine light.


In addition to the check engine light, you may also experience your vehicle malfunctioning in other ways, such as failing to start, idling differently than it usually does, and losing power while driving. 


If the gas in question isn’t in your car yet, but rather a canister, you can check if it’s old by its scent. Old gas will smell bad and have a slightly sour odor. It can also look darker and thicker than “good” gas, appearing almost mud-like. 


Worried About Old Gas Sitting In Your Car? Contract The Vault

Maintaining your vehicle isn’t always easy, but it’s an important thing to do to ensure your prized possession lasts for decades to come. Instead of worrying about gas sitting in your car and going back, let  The Vault help.


The Vault offers the best professional car storage and maintenance services in San Diego. Not only do we provide 24/7 security in one of our two gorgeous facilities, but we also provide quality maintenance services to ensure your vehicle is ready to drive whenever you need it next. 


Do you still have questions?  Contact us today to learn the simple steps to prepping a car for storage and beyond.