The rumble of a lawnmower engine is a familiar sound of summer, but what about the gas that fuels it? Do you need to empty the tank after every use, or can you let it sit for a while? This article will explore the shelf life of gasoline in lawn mowers, examining the factors that affect it, and the potential consequences of using old gas. We’ll also offer tips for storing gas safely and extending its lifespan.
Short Answer: The general rule of thumb is that gasoline stored in a lawn mower can last for 3-6 months, but its quality degrades over time. Several factors can influence this, including the type of gasoline, storage conditions, and the mower’s engine.
Understanding Gasoline Degradation
Gasoline is a volatile mixture of hydrocarbons that gradually breaks down when exposed to air and light. This process, known as “going stale,” leads to several changes in the fuel’s properties:
1. Evaporation: Gasoline is highly volatile, meaning it readily evaporates. Over time, this evaporation leads to a reduction in the fuel’s volume and a change in its composition.
2. Oxidation: Oxygen in the air reacts with the hydrocarbons in gasoline, forming gums and varnish-like deposits. These deposits can clog fuel lines, fuel filters, and carburetor jets, disrupting the flow of fuel to the engine.
3. Water Contamination: Even small amounts of water can mix with gasoline, causing corrosion and separation. This can also lead to engine damage.
How Long Can Gas Sit in a Lawn Mower?
The shelf life of gasoline in a lawnmower is not a fixed number. Several factors influence how long it can be stored safely:
1. Type of Gasoline:
- Regular Unleaded: This is the most common type of gasoline and has a shelf life of approximately 3-6 months.
- Ethanol-Blended Gasoline: Many gas stations sell gasoline blended with ethanol, a biofuel. Ethanol absorbs water and can accelerate gasoline degradation, reducing its shelf life to 2-3 months.
- Stabilized Gasoline: Stabilized gasoline is treated with additives that inhibit oxidation and evaporation, extending its shelf life to 12 months or more.
2. Storage Conditions:
- Air Exposure: Storing gasoline in an open container or a leaky tank allows oxygen to react with it, accelerating degradation.
- Temperature: Extreme temperatures, both hot and cold, can hasten the breakdown of gasoline. It’s best to store it in a cool, dry place.
- Sunlight: Ultraviolet radiation from sunlight can also contribute to gasoline degradation. Store it in a dark or shaded area.
3. Mower Engine Type:
- Modern Engines: Modern lawnmower engines are designed to handle fuel that’s slightly degraded, but they are not immune to the effects of very old gas.
- Older Engines: Older engines can be more sensitive to fuel quality and are more prone to problems with old gas.
Signs of Old Gas in a Lawn Mower
Several signs indicate that the gasoline in your lawn mower may be old or degraded:
- Difficulty Starting: The engine may take longer to start or sputter and stall, especially when cold.
- Loss of Power: The engine may run poorly or lose power, especially under load.
- Fuel Leakage: Old gas can cause leaks in the fuel system due to the build-up of deposits.
- Rough Idling: The engine may idle unevenly or stall.
- Increased Emissions: Old gas can produce more smoke and emissions.
How to Store Gas Safely
If you need to store gasoline for an extended period, here are some tips:
- Use a Clean, Sealed Container: Always store gasoline in a dedicated container designed for fuel storage. Choose a container that is airtight and free of leaks.
- Add Stabilizer: Use a gasoline stabilizer to slow down the oxidation process and extend its shelf life.
- Store in a Cool, Dry, and Dark Place: Avoid storing gasoline in direct sunlight or in extreme temperatures.
- Label and Date the Container: Clearly label the container with the date you filled it to track its age.
- Do not Fill the Container to the Top: Leave some space at the top of the container for expansion.
What to Do with Old Gas
If you find yourself with old gasoline that you no longer need, there are several options for disposal:
- Use it in a Small Engine: If the gas is not too old, you can try using it in a small engine, such as a string trimmer or leaf blower.
- Dispose of it Properly: Many local recycling centers or hazardous waste facilities will accept old gas. Check with your city or county for proper disposal options.
- Do not Pour it Down the Drain or on the Ground: This is harmful to the environment and can contaminate water sources.
Conclusion
The shelf life of gasoline in a lawnmower is influenced by several factors, including the type of gasoline, storage conditions, and the mower’s engine. While modern engines are somewhat tolerant of slightly degraded fuel, it’s best to use fresh gas whenever possible to ensure optimal performance and longevity. By following the tips for storage and disposal outlined above, you can minimize the risks associated with old gasoline and keep your lawnmower running smoothly for years to come.
FAQs
Q1: What happens to gasoline over time?
Gasoline is a volatile substance that breaks down over time. When exposed to air, the lighter hydrocarbons in gasoline evaporate, leaving behind heavier compounds that are less flammable and more likely to gum up your lawn mower engine. This process is known as “going stale”. Additionally, condensation can form in the fuel tank, leading to water contamination which can also damage your engine.
The rate at which gasoline deteriorates depends on factors like storage conditions, fuel additives, and the type of gasoline used. In general, gasoline starts to degrade after about 30 days, with its effectiveness significantly reduced after 3 months.
Q2: How long can I store gasoline in a lawn mower?
Storing gasoline in a lawn mower for extended periods is not recommended, especially if you’re using regular, non-stabilized fuel. If you only plan to store the mower for a few weeks, you should be fine. However, for longer storage, it’s best to empty the tank and use fuel stabilizer to prevent the fuel from going stale.
For extended storage of more than 3 months, it’s recommended to completely drain the fuel system and store the mower with a clean tank. Using a fuel stabilizer can also help preserve the quality of the gasoline for a longer period.
Q3: What are the signs of bad gas in a lawn mower?
Bad gas can cause a variety of issues in your lawn mower. The most common sign is difficulty starting the engine, especially if it’s been sitting for a while. You may also notice the engine running sluggishly, sputtering, or even stalling. If you see any of these signs, you may have bad gas in your lawn mower.
Another sign is the presence of a gummy residue in the carburetor or fuel lines. This residue can clog the fuel system and prevent the engine from running properly. In some cases, bad gas can also cause damage to your engine parts.
Q4: Can I add fresh gas to old gas?
While it might seem like adding fresh gas to old gas would dilute the problem, it’s not recommended. Old gasoline has already begun to break down and contain contaminants that can be harmful to your lawn mower’s engine. Mixing fresh gas with old gas will only prolong the degradation process and potentially lead to engine damage.
It’s best to completely drain the old gas and refill the tank with fresh, stabilized fuel. If you’re unsure about the condition of the fuel in your tank, it’s always best to err on the side of caution and drain it.
Q5: How can I prevent gasoline from going bad?
The best way to prevent gasoline from going bad is to use a fuel stabilizer. Fuel stabilizers are chemicals that slow down the deterioration process and prevent the formation of harmful deposits. They are readily available at most automotive and hardware stores.
You can also try to reduce the amount of air exposed to the gasoline by keeping the fuel tank full. This will help to minimize evaporation and slow down the degradation process. Additionally, storing the mower in a cool, dry place can help to further reduce the rate of deterioration.
Q6: How do I drain the gas from a lawn mower?
Draining the gas from your lawn mower is a relatively simple process. First, disconnect the spark plug wire to prevent the engine from starting accidentally. Then, locate the fuel shut-off valve (usually near the gas tank) and turn it to the “off” position.
Next, remove the gas cap and place a container underneath the fuel line drain (if applicable). Open the drain valve and allow the fuel to flow into the container. Once the tank is empty, close the drain valve and replace the fuel cap. You can then dispose of the old gas properly according to local regulations.
Q7: What is the best way to store a lawn mower for long periods?
For long-term storage of your lawn mower, follow these steps:
- Drain the fuel tank completely and clean it thoroughly.
- If possible, run the engine until it stops to empty any remaining fuel in the carburetor.
- Add a fuel stabilizer to the tank and run the engine for a few minutes to circulate it.
- Change the oil and filter.
- Clean and lubricate the air filter.
- Store the mower in a clean, dry place, preferably covered.
- Start the engine once a month to prevent the carburetor from sticking.
By following these steps, you can ensure your lawn mower is ready to go when you need it, even after being stored for a long time.