How Long Does Gasoline Last in the Fuel Tank Before It Expires?

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How Long Does Gasoline Last in the Fuel Tank

Gasoline, or gas for short, is a fuel we use to run our cars. It combusts to produce energy when we ignite the engine, allowing all the motor parts to operate well in our car.

However, your car may encounter certain operational troubles, linking the issues to the fuel in the car’s tank. Can gas expire in the tank, causing such problems? And how long does gasoline last in your car’s fuel tank before it goes bad?

This article answers these questions and gives tips on understanding when to change the gas in your car. You’ll also learn about the reasons that can lead to your car’s fuel losing its capacity. With rising gas prices, these are tips to pay attention to. 

Can Gas Go Bad in the Gas Tank?

The short answer to it is a profound yes. Every compound made from hydrocarbon has an expiration, and so does gasoline. And if the gas has been sitting in your car’s fuel tank for a long time and you haven’t ignited your engine for months, then the gas is bound to go bad.

What Should You Do if It Expires?

As soon as you see the signs of expiration on your car’s gasoline, your first step is to change the fuel immediately. It won’t necessarily cost you much if a professional does it for you. And if you change the oil yourself, the cost will be much lower.

However, according to Mechanic Base, an expert-led automobile information website, the cost of changing your old gas will depend on the type of oil used and how much oil needs to be changed. You’ll also need to check your motor oil based on the mileage that your vehicle provides.

How Can You Tell Your Fuel Has Expired?

If the gas in your automobile has degraded and you don’t change it, you’ll face various costly issues. There will be internal damage in many engine parts, the fuel lines will be clogged, and some features can even start corroding.

A few indicators will help you determine whether your fuel has gone bad or you can still use it. Following are the ways you can identify old gasoline in your car.

1.  The Indication to Check the Engine

Every car has an indicator that lights up when there’s something wrong with the engine. If your gasoline gets old and starts clogging the connections, it’ll trigger that indicator. Your car may still be running fine, but that indicator may tell you something’s wrong with the fuel.

As soon as you see this, take your car to a professional to get it checked up thoroughly. A proper investigation will bring the main issue to the surface. And if you want to care for your car, you shouldn’t ignore it.

2.  Operational Issues of Your Car

Gas gone bad will create operational problems in your car. This means the engine won’t start, the ignition will be off, and your car suddenly stopping while driving.

All these indicate that the fuel has expired and is clogging up various parts of your car. It needs immediate replacement by a professional, as you also need to check if there’s any internal damage.

3.  Changes in Appearance and Smell

When gasoline expires, it’ll have a sticky glue-like appearance. Besides, it’ll look muddy and lack the fuel’s characteristic color. That consistency is enough to clog pipes and ruin many of your car’s internal parts.

Expired gas also has a foul odor, which can be described as a sour smell. It’s different than the characteristic smell we get from these fuels. This indicates that your car’s gas has degraded and needs immediate replacement.

What is the Shelf Life of Gasoline?

Pure gasoline has a long shelf life. Regular gasoline typically lasts three to six months if stored in a tightly sealed can. It’ll likely deteriorate if you let gas sit in your car tank. Add fuel stabilizers, and it’ll last for around a year.

To understand what determines the shelf life of gasoline, you also need to understand its chemical composition. This will also explain why gas can degrade in a sealed can or your car’s fuel tank. Besides, you can remodel your garage to optimize it for proper storage for your car’s gasoline cans.

Why Does Gasoline Degrade in the Tank?

Three factors commonly lead to the degradation of gas. All of these are connected to the fuel’s chemical composition, other things being mixed in it, and how air and water can react with the fuel.

Oxidation of Gas

Gasoline is a hydrocarbon with a complex bond between hydrogen and carbon atoms. If you keep the canister cap loosely closed or gas sits in your car’s engine for a while, oxygen will start bonding with the hydrocarbon structure. Oxidation happens, changing the entire chemical makeup of the gasoline.

If that happens, your fuel won’t combust efficiently, and your car won’t function well.

Water Finds Its Way in

Most gasoline has a certain amount of ethanol mixed into it. Ethanol is notorious for attracting water from the air, which dilutes the fuel. It shortens the shelf life and causes crystalization in lower temperatures, which means the gasoline won’t combust as well as it usually does in the presence of water.

Water can also make its way inside and into the fuel tank if something in your car remains loose, allowing water to seep in.

Some of the Fuel Evaporates

Unlike pure gasoline, the regular gas that we use has various hydrocarbons mixed into it. That’s because some fuels are heavier in structure, so they need fluidity to travel to multiple parts of the car for the ignition to work correctly. For this reason, lighter hydrocarbons that evaporate quickly are mixed in the fuel.

During summer, your car will do just fine with heavier fuel, as it’s easier for the engine to heat up and pull the gasoline. This means less volatile hydrocarbons, so they’ll stay good longer.

However, it’s hard for the engine to warm up during the winter. For this reason, people often need lighter gasoline, which has more volatile compounds, making it easier to expire.


Like every fuel and anything that reacts with oxygen, gasoline can also expire anywhere between one month to one year. And if it has been sitting long in the tank, you’ll need to change it.

Gasoline doesn’t last too long in the fuel tank, and it’ll give your car issues if it’s past the expiration. If your car starts acting up, check the fuel immediately. With proper time, care, and regular gasoline change, your car will stay in good condition for longer.

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