How Long Is Gas Good For a Lawn Mower?

Spring has sprung, and the sun is shining. It’s time to get your lawnmower out of storage and get ready for the season of mowing. But before you start the engine, you may be wondering – how long is that gas you have in the tank actually good for?

You know that gas goes bad, and you probably know you shouldn’t leave it in your car tank for too long, but what about your lawnmower? The answer isn’t a simple one, as there are several factors that impact how long gasoline stays usable. This article will explore those factors, the signs of bad gas, and some tips for storing your gas safely so you can be sure your lawnmower is ready to go when you are.

A Quick Overview

Gasoline degrades over time due to a process called oxidation, where it reacts with oxygen in the air. This process produces gum and varnish, which can clog your mower’s fuel system and prevent it from running properly. The time it takes for gas to go bad depends on several factors, including the type of gas, storage conditions, and the presence of stabilizers. Generally, you can expect fresh gasoline to remain usable for 3 to 6 months if stored correctly.

Understanding the Degradation Process

Why Does Gas Go Bad?

The primary culprit behind gas degradation is oxidation. When gasoline is exposed to air, it reacts with oxygen, leading to the formation of harmful compounds. These compounds are collectively known as “gums and varnishes,” which are sticky residues that can accumulate in the fuel system of your mower.

What Are Gums and Varnishes?

  • Gums: These are sticky, rubbery substances that can clog fuel lines, fuel filters, and carburetor jets.
  • Varnishes: These are hard, resinous deposits that can build up inside fuel tanks and fuel lines.

Gums and varnishes can cause a range of problems for your lawnmower, including:

  • Difficulty starting: Clogged fuel lines or filters can prevent fuel from reaching the engine.
  • Rough running: Clogged carburetor jets can lead to uneven fuel flow and a rough idle.
  • Engine stalls: Severe gum or varnish buildup can completely block fuel flow, causing the engine to stall.
  • Reduced power: A restricted fuel flow can reduce the amount of fuel reaching the engine, leading to decreased power output.

How Long Does Gas Last?

Factors Affecting Gas Longevity

The lifespan of gasoline depends on various factors:

  • Type of Gasoline: Ethanol-blended gasoline, commonly used in the US, tends to degrade faster than pure gasoline.
  • Storage Conditions: The more exposure to air, light, and heat, the faster the degradation process.
  • Additives: Gasoline stabilizers can slow down the oxidation process, extending the gas’s usable life.

General Rule of Thumb

As a general guideline, fresh, untreated gasoline can remain usable for 3 to 6 months if stored properly. However, this timeline can vary depending on the factors mentioned above.

Ethanol-Blended Gasoline

Ethanol-blended gasoline, which is widely available in the US, can degrade more rapidly than pure gasoline. Ethanol is highly hygroscopic, meaning it readily absorbs moisture from the air. This moisture can contribute to the formation of gums and varnishes, accelerating the degradation process. Ethanol-blended gas is typically recommended for use within 30 days.

Signs of Bad Gas

Visual Inspection

  • Color Change: Fresh gasoline is typically clear or slightly yellow. Over time, it can turn darker, ranging from amber to brown.
  • Sediment: Look for any sediment or debris at the bottom of the fuel tank. This is a clear indication of degradation.

Operational Issues

  • Difficulty Starting: If your lawnmower takes longer than usual to start or struggles to turn over, it could be a sign of bad gas.
  • Rough Running: A sputtering or irregular engine idle is another indicator of potential fuel problems.
  • Loss of Power: Noticeable power loss or a decrease in overall engine performance could indicate a clogged fuel system.

Storage Tips for Gasoline

Minimize Air Exposure

  • Full Tank: Always keep your fuel tank full to minimize air space in the tank, reducing oxygen exposure.
  • Seal Tightly: Ensure the fuel cap is securely sealed to prevent air from entering the tank.
  • Store in a Cool, Dark Place: Store gasoline containers in a cool, dry, and dark location to protect it from heat and light.

Use Stabilizers

  • Fuel Stabilizers: These are additives that slow down the oxidation process, extending the shelf life of gasoline.
  • Follow Instructions: Always follow the manufacturer’s instructions for using fuel stabilizers.

Final Thoughts

Although it’s a good idea to use fresh gas for optimal performance, you can extend the life of gasoline by taking the necessary precautions. By understanding how gas degrades and implementing proper storage practices, you can keep your lawnmower running smoothly throughout the season. Remember, using old gas can lead to costly repairs, so it’s always worth taking the time to ensure your fuel is fresh and ready to go.

FAQs

How long can gas sit in a lawnmower before it goes bad?

Gas can sit in a lawnmower for a few months, but it’s best to use it within 30 days for optimal performance. After that, the gas starts to degrade, losing its potency and becoming less efficient. This is due to the volatile nature of gasoline, which evaporates and oxidizes over time.

However, the exact time gas remains usable varies based on several factors, including the quality of the fuel, storage conditions, and the type of lawnmower. Factors like the type of gasoline additives and the presence of stabilizers play a role in how long gas remains usable.

What happens when gas goes bad in a lawnmower?

When gasoline degrades, it loses its energy content and may contain gum, varnish, and other residues that can clog the fuel system. This can result in difficulty starting the lawnmower, poor engine performance, and potential damage to the engine.

Symptoms include stalling, sputtering, and inconsistent engine operation. The engine might run sluggishly or experience difficulty reaching full speed. The presence of gummy deposits can also block fuel lines, fuel filters, and even the carburetor.

How can I tell if gas has gone bad?

One telltale sign of bad gas is a strong odor of gasoline. Fresh gas should have a mild, sweet smell, while aged gas can smell pungent and sour. Another indication is a change in the gas’s color. Fresh gas is typically a clear, amber color, while older gas can appear cloudy or discolored.

You can also check for the presence of sediment or debris in the gas tank. If you notice any of these signs, it’s best to discard the old gas and replace it with fresh gasoline.

How can I prevent gas from going bad in a lawnmower?

The most effective way to prevent gas from going bad is to use fuel stabilizers. These additives help slow down the oxidation process and prevent the formation of harmful deposits. You can add a fuel stabilizer to your gas tank before storing your lawnmower for an extended period.

Another tip is to use fresh gasoline. If you know you won’t be using your lawnmower for a while, it’s better to drain the tank and store the gas in a separate container, preferably one specifically designed for fuel storage.

How long can I store gas in a lawnmower?

It’s generally not advisable to store gasoline in a lawnmower for more than a few months, even with a stabilizer. Over time, the fuel can still degrade and cause problems. If you need to store gas for a longer period, it’s best to transfer it to an airtight container and add a fuel stabilizer.

It’s important to note that storing gas in a lawnmower can attract pests and potentially pose a fire hazard. Always store gasoline safely, in a cool, dry place away from any heat sources.

How do I dispose of old gas from a lawnmower?

Disposing of old gas properly is essential to protect the environment. Do not pour it down the drain or onto the ground. It is best to contact your local waste management facility for instructions on how to properly dispose of the gasoline.

Many gas stations offer recycling programs for old motor oil and gasoline. Check with your local gas stations or recycling centers to find out if they participate in such programs.

What happens if I use old gas in my lawnmower?

Using old gas in your lawnmower can result in several problems, including poor engine performance, engine damage, and even fire hazards. The degraded gas can cause fuel lines and the carburetor to become clogged, leading to engine stalling, sputtering, and difficulty starting.

In extreme cases, the accumulated deposits can cause significant damage to the engine, requiring expensive repairs. Moreover, the evaporation of volatile compounds from old gas can create flammable vapors, increasing the risk of fire hazards. It’s always better to use fresh gasoline for optimal performance and safety.

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