Skip the auto shop - Our mechanics make house calls

Does Gasoline Expire?

Old Gasoline

Gasoline does expire if it is left unused for a long period of time. The problem with gas is its volatility. A volatile substance is prone to separating and vaporizing. This is especially bad if the fuel vapor has an easy way out of the tank, allowing it to just evaporate away into the air. If this is not the case, then it is more likely that the fuel will just be significantly less potent than new gasoline.

How to spot bad gas

If gas is already in the tank of a vehicle, getting it out is a hassle. If the gas is old enough that siphoning the tank to test the fuel is a viable option, then it is more worthwhile to simply replace the fuel. If the fuel is in a gas can or similar container, then there are a few signs to look out for:

  • Darkened color: As gas ages, it usually darkens in color. It helps to have new gas on hand to compare the two.

  • Sour smell: Similar to spoiled food, spoiled gas smells different than new gasoline. Gas fumes are not healthy to breathe, so do not smell gas close up. Gas is a noticeable scent to anyone in proximity to it, so if the smell is sour or “off” it may be bad.

Dangers of bad gas in the fuel system

  • Bad gas can break down and leave residue along the hoses and fittings of the fuel system

  • Water that may be present in the gas can separate out and cause corrosion in the fuel system

  • If the gas is so old that it can no longer run the engine, it may be difficult to get it out of the tank and to get new fuel into the fuel system

The amount of time it takes gas to expire depends on the climate, age of the gas, and formula of the gas, along with many other factors. Use fuel stabilizer in a vehicle that is going to be parked for a long time. Any time over a month qualifies.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
Icon-warranty_badge-02

Skip the repair shop, our top-rated mechanics come to you.

At your home or office

Choose from 600+ repair, maintenance & diagnostic services. Our top-rated mechanics bring all parts & tools to your location.

Fair & transparent pricing

See labor & parts costs upfront, so you can book with confidence.

12-month, 12,000-mile warranty

Our services are backed by a 12-month, 12,000-mile warranty for your peace of mind.

Get A Quote

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.

GET A QUOTE

More related articles

How to Renew Your Car Registration in Oklahoma(DELETED)
Having your car registered with the Oklahoma Tax Commission is an important part of driving legally in this state. You will need to do this within 30 days of moving to Oklahoma...
How to Transfer a Car Title in Idaho
In order to prove ownership of a car, you must have the title. However, when a car is sold, given away or inherited, the title needs...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...


Related questions

Q: My gas gauge keeps fluctuating from empty to full and everything in between.

The symptoms you are having may be related to a mechanical issue, or an electrical issue. If the problem is electrical, you will want to check the wiring terminal that connects to the fuel pump. You may need to drop...

Q: Car won't start after being parked

When the key is turned and nothing happens could mean several things; you have a bad battery (most common), the switch is bad, or the starter is not working. If you hear a click when you turn the key and...

Q: Car running sluggish then dies - 1988 Mercedes-Benz 420SEL

Hello. I would check the fuel filter first. If the filter is clogged then this will occur. If the fuel filter is fine then the air flow meter needs to be checked. This is the most common part to fail...