Posted by Zane Winberg on

Can gas really go bad if it is left unused in a storage container or even tank for too long? Some people think that gas lasts basically forever and that people who spend money on fuel additive or stabilizer are just throwing their money away. So what’s the deal?

Well, gas can, in fact, degrade and go bad over time. This degradation can lead to any number of problems like hard starts, rough running, and even not starting or running at all.

Why does gas go bad? The gasoline and diesel fuel you use in your cars, trucks, lawn mowers, boats, RVs, and anything else with a fuel engine is brewed specifically to an exact chemical composition.


One of the most important elements of this composition is volatility – what it takes for the fuel to vaporize and so it can be efficiently burned by an engine. The higher the volatile elements in the fuel tend to evaporate into gas over time naturally (since that is what they are designed to do). Without these more volatile elements, the gas is left…less volatile and therefore less effective. Even if the fuel will get your engine going, your engine will not be able to efficiently use it which will lead at least to higher energy costs and at worst severe engine problems. You can partially avoid this problem by ensuring that gas tank caps and gas storage containers are shut tight.


Oxidation is another problem that tends to lead to fuel degradation. When fuel oxidizes new compounds are actually formed that can gum up and clog the fuel system and engine. Removing these buildups can be costly and difficult. Best not to leave fuel in the lines or add a fuel stabilizer that stops oxidation.


Condensation can also build up in fuel lines and cause fuel to go bad. This is more likely to happen if the fuel line has been evacuated for storage purposes. So, it seems there is a catch: Leave fuel in the lines and risk oxidation and evaporation or empty the fuel line and risk water damage. There is a simple solution. Keep fuel lines full for storage, ensure they are airtight, and add a fuel stabilizer.

How to tell if your gas is bad

Oxidized fuel turns darker over time and usually smells sour. Check old gasoline in a glass container and compare it to new gas.

How long does it take for gas to go bad?

That depends on a number of factors. For one, it's hard to know how old the gas you just bought actually is. It may be fresh from the refinery, or it may be a month old already by the time you top off your tank. Some gasoline is mixed with better or more oxidation inhibitors than others.

It's a good rule of thumb to avoid leaving gas in your tank or a storage container for more than a couple of months or to always add a fuel supplement stabilizer.

CleanBoost® Maxx™ Fuel Additives

Planning on storing some fuel soon? Make sure you get some fuel supplement stabilizer today! Try our CleanBoost Maxx!

CleanBoost® Maxx™

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