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Does Ethanol-Free Gas Go Bad? Fuel Shelf Life Comparisons

Does Ethanol-Free Gas Go Bad? Fuel Shelf Life Comparisons

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Paul Brown

Ethanol-free gas can be expensive, so you don’t want to have to waste it. If you are staring at a dusty container of ethanol-free gas in your shed and wondering if you can still use it, I’m going to give you the quick answer and then provide you some more useful information on this fuel.

Does ethanol-free gas go bad? Yes, ethanol-free gas can go bad. Ethanol-free gas is suitable for use for around six months if correctly stored and sealed. It lasts longer than gas with ethanol in it can still degrade, especially if it’s been exposed to atmospheric conditions.

Although ethanol-free gas does go bad, you can mitigate the risk of degradation by storing it correctly. Read on to find out why ethanol-free gas is an excellent choice for your equipment and learn some essential tips about how to store it correctly.

What Is The Difference In Shelf Life Between Ethanol-Free and Ethanol-Based Gas?

If your weed eater or leaf blower runs on a two-stroke engine, you have a choice between mixing your own gas/oil solution or buying a commercial premix! With the DIY approach, your fuel mix will have an incredibly short lifespan without stabilizers, and a wrong mix can easily damage the engine.

Let’s look at a side by side comparison of storage life for gas with and without ethanol, as well as a commercial premix solution.

Fuel TypeOpened Storage Life*
Gas with ethanol from pump2 Weeks – 3 Months
Ethanol-free gas from the pumpUp to 6 Months
Commercial premixed (ethanol-free)Up to 2 Years

As you can see, there is a dramatic difference when using fuel from the local service station compared to purchasing commercially premixed ethanol-free fuel. But why?

Gasoline is actually a carefully calibrated substance, a mixture of carbon and nitrogen atoms along with octane-enhancing additives (source). This delicate balance degrades with time.

Oxidation and degradation of the igniting quality of gas begin as the fuel is opened and exposed to the atmosphere. The fuel at the pump has already been exposed. Think of it as an open container.

Commercial premixed fuels on the other hand like Trufuel (link to Amazon) are factory sealed. When you open them, the process of oxidation begins. But fuel pump gas may have been exposed to oxidation for quite some time already. There is no way to know.

You can extend the storage life somewhat (as well as protecting your small engine) by using ethanol-free gas in your mix. Ethanol-free gas allows you to use the fuel you had in storage for over six months. Let’s see why.

What Does Ethanol Do To Gasoline?

Ethanol-based gas is widely available from sellers and distributors. In fact, chances are that when you pump gasoline at your local convenience store, it contains around 10% ethanol.

fuel pump gas contains ethanol

Ethanol is a type of alcohol that is derived from corn. Such additive, when mixed with the fuel, allows the gasoline to burn thoroughly during the combustion process, limiting the CO2 emissions released by the engine (source).

But here’s the issue: Ethanol tends to attract moisture and particles of water from condensation within the fuel tank as well as from external sources. When you are storing Ethanol for a prolonged time, the attracted water will merge with the fuel, creating bubbles.

A study conducted back in 2018 found that ethanol causes corrosion and degradation of metals and fuel lines in engines (source). This is especially problematic in small engines like powered yard tools.

While automobiles and more complex 4-stroke engines can deal with ethanol through a computerized system that regulates the fuel’s flow, your simpler 2-stroke won’t cope as well. Aside from starting to erode the engine’s internal parts and crankcase, water in a 2-stroke engine can lead to poor performance and engine failure.

Click below to read my in-depth review of the problems that ethanol causes for small engines:

Ethanol-Free Gas 

Since ethanol-free gas lacks alcohol, it is less likely to attract particles of water into the fuel tank. As water is the most common cause of fuel spoilage, ethanol-free gas has an extended shelf life of up to 6 months. However, other factors such as a drastic change in temperature and direct sunlight can contribute to reduced shelf life.

Ethanol-free gas can be more challenging to find and is less common than ethanol-based fuel. If you use your equipment a limited number of times every year, manufacturers recommend buying pre-blended fuels that you can add quickly to the tank without having to create your premix. Such products often include stabilizers and ethanol-free gas and have a shelf life of over two years.

Learn how these commercial premix fuels stack up: Read Stihl Motomix vs Premixed Alternatives: 4 Products Compared

Ethanol-Based Gas

Ethanol-based gas is readily available from any distributor, but its alcohol content limits its shelf life. Within this timeframe, the stored fuel will attract moisture, which, in turn, will create bubbles of water within the gasoline. 

A similar process will happen in the gasoline leftover in the tank and fuel line of your two-stroke. That’s why you should always drain your tank and carburetors of your 2-stroke yard tools for the winter.

While picking the best ethanol-based gas, avoid using any fuel that has an alcohol content higher than 10%. Alongside it, for your premix, use only fuel with an octane rating higher than 89 and synthetic “ashless” (residue-free) oil.

Even if you have changed the premix before going bad, ethanol-based gas can be detrimental for a 2-stroke engine of your if the blend does not fit in these parameters.

See, it’s complicated. That’s why I just buy commercially premixed like Trufuel (link to Amazon). It stores for years and I know the quality and mix ratio is right for my powered yard tools.

This brings us to our next point…

Gas And Oil Premixed Shelf Life

Whether you have created the premix with ethanol-free or ethanol-based gasoline, the blend will have another potential spoilage cause: the oil.

An oil that is sitting in a tank for longer than a month will lose viscosity. Therefore, it will see a reduced power of lubricating the crankcase and piston of the engine correctly.

To increase the shelf life of premixes created with ethanol-based or ethanol-free gasoline, manufacturers recommend adding stabilizers. Aside from preventing the oil from going bad, such compounds will bond with the water particles and re-absorb them.

Generally, the shelf life for premix is:

  • Home-made, without stabilizers – 2-weeks
  • Home-made, with stabilizers – 12 months
  • Store-bought – 2+ years (check user manual)

Your mileage may vary (literally) with the homemade premix concoctions. There are just so many variables that can impact this: ethanol vs non-ethanol of course. But there is also:

  • the quality of the gas used
  • quality and age of the oil
  • quality of the stabilizers…

It’s a bit of a crapshoot but the above-listed guidelines are the generally accepted timelines.

Why Ethanol-Free Gas For Your 2-Stroke Handheld Equipment?

Cars and newer four-stroke engines include a computerized system that allows them to regulate the flow of fuel based on the amount of water it contains.

However, your two-stroke handheld outdoor equipment runs on a much simpler engine system. While there are fewer pieces to break in such engines, correct lubrication, oil-to-gas ratio, and gasoline quality are essential.

Ethanol-free has several benefits for your outdoor power tools:

  • If sealed properly, ethanol-free gas lasts longer. This means less waste of product and money.
  • Ethanol-free gas increases the performance of the engine and reduces the risk of power loss and engine failure.
  • There is a lower chance of the Ethanol in the premix to create damage to the tank, engine, and gum parts a 2-stroke engine.

How To Store Ethanol-Free Gas To Increase Its Lifespan

As we have seen, water and moisture make up the most common cause of fuel spoilage. Yet, if you are not storing the gas properly, several other factors can affect the quality of your premix. To ensure a shelf life of at least six months, you should:

  • Store the gas in a non-spill, approved fuel storage container
  • Ensure that the tank is airtight and completely sealed
  • Keep the tank away from direct sunlight
  • Avoid sudden or drastic changes in temperature in the room where you keep the container.
  • Keep the tank at least 15 meters away from any ignition sources
  • Do not overfill the container as gasses can expand and need space for this process

Remember that gasoline is a delicate balance of ingredients. Disturbing that balance impacts its shelf life!


Ethanol-free gasoline is an optimal choice for your handheld outdoor equipment. Thanks to the lack of alcohol in it, this type of gas will not tend to attract particles of water and moisture into the fuel tank, line, or storage container.

The increased shelf-life makes it the best choice if you are not using your weed eater or leaf blower often.

Yet, ethanol-free gasoline can be difficult to find since, per regulations, most cars are required to use ethanol-based gas. Nevertheless, if you like to trim your garden occasionally or once or twice per season, you should consider buying a pre-blended fuel that incorporates non-ethanol alcohol, stabilizers, and high-quality oil and fuel.

We recommend the following ethanol-free fuels:

TruFuel 4-Cycle Fuel for Outdoor Power Equipment (link to Amazon)

TruFuel 2-Cycle 50:1 Pre-Blended Fuel for Outdoor Power Equipment (link to Amazon)

Stihl MotoMix Premixed Fuel 50:1 (link to Amazon)

Curious how Stihl Motomix and Trufuel compare? Read my detailed analysis.