How Long Can Gasoline Last in Your Tank?

Many drivers are always on the lookout for ways to cut their spending at the gas pump. They may choose to buy the most fuel-efficient vehicle, such as a Honda Insight or Toyota Prius. However, this isn’t an option for everyone, especially those who need larger cars for work purposes.

Trucks and large SUVs usually use more gas than smaller cars. For some drivers, it makes sense to limit their daily driving as a method of saving money. However, letting gas sit in your car’s tank for too long isn’t a good idea. What’s the average shelf life of gasoline, and what can you do to extend it?

How long does gasoline last?

Different types of fuel have different lifespans. For conventional gasoline, it usually lasts anywhere from three to five months in your gas tank. Diesel fuel can last twice as long, around six to twelve months.

The reason these numbers are so broad is that it’s hard to tell how old the gas actually is. It may have been sitting inside the gas pump for a month already before you came to fuel up. You also don’t know how long the gas was stored at the refinery before it was transported to the gas station.

Generally, it’s best to be cautious and use all the gas in your tank before a few months have passed. When gasoline goes bad, it won’t burn correctly inside the engine. It could also be exposed to water contamination, which may lead to corrosion in the fuel system. The same goes for other things that use gasoline, like lawnmowers or scooters.

How to tell if the fuel has gone bad

You’ll be able to tell if your gasoline has gone bad just by starting your car. If it has a rough idle, stalls frequently during acceleration, or fails to start at all, your gas has gone bad. Sometimes, bad gasoline will also cause the check engine light to illuminate.

You can also tell if gasoline is bad by its appearance. If it’s darker than usual or has a sour smell, it’s probably bad. Always consult a mechanic on how to best remove or fix bad gasoline in a car. There are also a few steps you can take to keep your gas from expiring. 

Don’t buy more than you’ll use

A man with mask makes gasoline from a gas station in Turin during on the Italy Extends Coronavirus Lockdown
A man putting gasoline in his vehicle | Stefano Guidi/Getty Images

Your tank should always be as full as possible to reduce water condensation. If you know you’re about to put your car in storage for the winter, don’t leave its tank half full beforehand. You should also avoid topping off your tank, which can damage the tank’s vapor recovery system.

Find the freshest fuel

As annoying as it might be, try to find the gas station with the most customers to purchase your fuel. Since the pumps are being used often, there’s a good chance that the fuel is always new. Get to know the gas station’s peak activity times so that you can avoid crowds of cars.

Make sure the gas cap fits

The gas cap keeps out water, dirt, and other things that could potentially damage the fuel. If it’s lost or doesn’t fit, your fuel won’t have that protection. Fortunately, a new gas cap is a quick and inexpensive fix.

Use a fuel stabilizer

If you think your car’s gas has already gone bad, you may be able to fix it with a fuel stabilizer. Fill the gas tank to the top, add the stabilizer, and then drive the car for at least 10 minutes. This will ensure that the stabilizer has had time to circulate through the fuel system. After adding the fuel stabilizer, the gas in your tank could last for up to a year.