The end of mowing season is approaching, and that means preparing your lawn mower for its long winter nap. One of the most common questions that arises during this process is: should you store your lawn mower with a full tank of gas? The answer isn’t as straightforward as you might think, and depends on several factors. Let’s delve into the pros and cons to help you make the best decision for your machine and storage environment.
Understanding the Gasoline Problem
Gasoline isn’t the stable, unchanging substance we often assume it is. It’s a complex blend of hydrocarbons that can degrade over time, leading to various problems in your lawn mower. Understanding the science behind fuel degradation is crucial to making an informed decision about storing your mower.
The Evaporation Process
One of the primary issues is evaporation. Gasoline is volatile, meaning it readily evaporates, especially in warmer temperatures. As the more volatile components evaporate, the remaining fuel becomes thicker and less combustible. This can lead to difficulty starting your mower in the spring.
Water Absorption
Modern gasoline often contains ethanol, an alcohol that’s added to boost octane and reduce emissions. However, ethanol is hygroscopic, meaning it readily absorbs water from the atmosphere. Water in your fuel tank can cause several problems, including:
- Corrosion of metal parts in the fuel system.
- Separation of the fuel into distinct layers, with water and ethanol sinking to the bottom.
- Difficulty starting the engine, as the water-ethanol mixture doesn’t burn well.
Gum and Varnish Formation
As gasoline degrades, it can form gummy deposits and varnish. These sticky substances can clog fuel lines, carburetors, and other engine components, leading to poor performance or even complete engine failure. This is especially problematic in small engines like those found in lawn mowers.
The Case for Storing with a Full Tank
Despite the potential problems with gasoline degradation, there are compelling reasons to store your lawn mower with a full tank.
Minimizing Condensation
A full tank of gas minimizes the amount of air inside the tank. This reduces the potential for condensation to form, especially in environments with fluctuating temperatures. Condensation occurs when warm, moist air cools and releases water. This water can then mix with the fuel and cause corrosion. A full tank helps to displace air, reducing the risk of condensation.
Preventing Tank Rust
In older lawn mowers with metal fuel tanks, an empty tank can be susceptible to rust. The exposed metal surfaces can corrode due to moisture and oxygen in the air. A full tank of gas protects the metal from direct exposure to air and moisture, helping to prevent rust formation.
Fuel Stabilizer Effectiveness
If you’re using a fuel stabilizer (and you should be!), a full tank allows the stabilizer to work more effectively. The stabilizer needs to be thoroughly mixed with the gasoline to protect it from degradation. A full tank ensures that the stabilizer is evenly distributed throughout the fuel system.
The Case Against Storing with a Full Tank
There are also valid arguments against storing your lawn mower with a full tank of gas. These concerns primarily revolve around the risks associated with old, untreated fuel.
The Stale Fuel Problem
As mentioned earlier, gasoline degrades over time. If you store your lawn mower with untreated fuel, it’s likely to become stale and cause problems when you try to start it in the spring. Stale fuel can lead to:
- Hard starting.
- Poor engine performance.
- Clogged fuel lines and carburetor.
The Risk of Fuel Leaks
A full tank of gas increases the risk of fuel leaks, especially if your mower has older fuel lines or seals. Temperature fluctuations can cause the fuel to expand and contract, putting stress on the fuel system. If there are any weak points, leaks can occur, creating a fire hazard and a potential environmental issue.
Ethanol-Related Issues
While a full tank minimizes condensation, the presence of ethanol in the fuel can still be a problem. Ethanol attracts water, and even a small amount of water can cause corrosion and fuel separation. If you’re using gasoline with a high ethanol content, it’s especially important to use a fuel stabilizer.
The Solution: Fuel Stabilizer and a Full Tank
The best approach is to combine the benefits of a full tank with the protective properties of a fuel stabilizer.
How Fuel Stabilizer Works
Fuel stabilizers are chemical additives that prevent gasoline from degrading over time. They work by:
- Inhibiting oxidation, which is a major cause of fuel degradation.
- Preventing the formation of gum and varnish.
- Protecting against corrosion.
- Stabilizing ethanol and preventing it from absorbing water.
Choosing the Right Fuel Stabilizer
There are many different fuel stabilizers on the market. Look for a product that is specifically designed for small engines and that protects against ethanol-related problems. Read the label carefully and follow the manufacturer’s instructions.
The Step-by-Step Process
Here’s the recommended process for preparing your lawn mower for winter storage:
- Fill the gas tank completely: This minimizes air space and reduces the risk of condensation.
- Add fuel stabilizer: Follow the manufacturer’s instructions for the correct amount of stabilizer to add per gallon of gasoline.
- Run the engine: Run the engine for several minutes to allow the stabilized fuel to circulate throughout the fuel system, including the carburetor.
- Consider draining the carburetor: For added precaution, after running the engine with stabilizer, you can drain the carburetor. This removes any remaining fuel in the carburetor bowl, further reducing the risk of gum and varnish formation. Consult your owner’s manual for instructions on how to drain the carburetor.
- Store the mower in a dry place: Protect your mower from the elements by storing it in a shed, garage, or basement.
Alternative Options: Emptying the Fuel Tank
Another option is to completely empty the fuel tank before storing your lawn mower. This eliminates the risk of fuel degradation and potential leaks.
The Procedure
- Run the engine until it stalls: This will use up most of the fuel in the tank and fuel lines.
- Disconnect the fuel line: Disconnect the fuel line from the carburetor and drain any remaining fuel into a suitable container.
- Drain the carburetor: As mentioned before, draining the carburetor is essential to remove any residual fuel that could cause problems.
- Dispose of the fuel properly: Do not pour old gasoline down the drain or onto the ground. Take it to a local recycling center or hazardous waste collection facility.
Considerations
Emptying the fuel tank can be a good option, but it also has some drawbacks. It leaves the fuel tank vulnerable to rust and condensation. It also requires you to handle and dispose of gasoline, which can be messy and potentially hazardous.
Beyond the Fuel Tank: Other Winterization Steps
Preparing your lawn mower for winter storage involves more than just dealing with the fuel tank. Here are some other important steps:
Cleaning the Mower
Thoroughly clean your mower to remove grass clippings, dirt, and debris. This will prevent corrosion and make it easier to inspect the mower for any damage. Pay particular attention to the underside of the deck, where grass clippings can accumulate and trap moisture.
Changing the Oil
Change the engine oil before storing your mower. Old oil can contain acids and contaminants that can corrode engine parts over the winter. Use the type of oil recommended in your owner’s manual.
Replacing the Air Filter
A clean air filter is essential for proper engine performance. Replace the air filter if it’s dirty or damaged.
Sharpening or Replacing the Blade
A sharp blade will give you a cleaner cut and reduce stress on the engine. Sharpen the blade if it’s dull, or replace it if it’s damaged.
Checking the Spark Plug
Inspect the spark plug for wear and tear. Replace it if it’s fouled or damaged.
Lubricating Moving Parts
Lubricate all moving parts, such as the wheels, axles, and cables, with a suitable lubricant. This will prevent rust and ensure smooth operation next season.
Battery Care (for Electric Start Mowers)
If your lawn mower has an electric start, remove the battery and store it in a cool, dry place. Charge the battery periodically throughout the winter to keep it in good condition. Alternatively, use a battery maintainer.
Making the Right Choice for Your Lawn Mower
So, should you store your lawn mower with a full tank of gas? The answer is yes, if you use a fuel stabilizer. A full tank, combined with a fuel stabilizer, minimizes condensation, prevents rust, and ensures that the stabilizer is evenly distributed throughout the fuel system.
However, if you’re not comfortable using a fuel stabilizer, or if you’re concerned about fuel leaks, emptying the fuel tank may be a better option. Just be sure to take steps to protect the tank from rust and condensation.
Ultimately, the best choice depends on your individual circumstances and preferences. By understanding the pros and cons of each approach, you can make an informed decision that will help to keep your lawn mower in good condition for years to come. Proper winterization is key to ensuring a smooth start to the next mowing season.
Why is it generally recommended to avoid storing a lawn mower with gasoline in the tank for extended periods?
Storing a lawn mower with a full tank of gasoline over the off-season can lead to several problems. Gasoline can degrade over time, forming gums and varnishes that can clog the carburetor and fuel lines. This degradation is accelerated when the fuel is exposed to air and temperature fluctuations within the tank. The result is a lawn mower that is difficult to start or runs poorly when you try to use it again.
Furthermore, the presence of gasoline poses a fire hazard, particularly if the lawn mower is stored in a confined space. Leaks or spills can create dangerous fumes, increasing the risk of ignition. Additionally, gasoline can corrode certain components of the fuel system, leading to expensive repairs. Emptying the tank or using a fuel stabilizer are better alternatives to prevent these issues.
What is fuel stabilizer and how does it help when storing a lawn mower with gasoline?
Fuel stabilizer is a chemical additive designed to prevent the degradation of gasoline during storage. It works by inhibiting the oxidation process that causes gasoline to break down and form gums and varnishes. By adding fuel stabilizer to the gasoline in your lawn mower’s tank, you can significantly extend the fuel’s lifespan and prevent it from damaging the engine components.
To use fuel stabilizer effectively, add the recommended amount to the gasoline in the tank according to the manufacturer’s instructions. Run the engine for a few minutes to ensure the stabilizer circulates throughout the fuel system, including the carburetor. This treatment will help keep the fuel fresh and prevent clogs from forming, ensuring your lawn mower starts easily and runs smoothly when you need it next.
What are the benefits of completely emptying the gas tank before storing a lawn mower?
Completely emptying the gas tank before storing your lawn mower eliminates the risk of gasoline degradation and the formation of harmful deposits within the fuel system. This prevents the carburetor and fuel lines from becoming clogged, ensuring easier starting and smoother operation when you next use the mower. Emptying the tank also minimizes the potential for fuel leaks and reduces the fire hazard associated with storing gasoline indoors.
By removing the gasoline, you also prevent the corrosion of fuel system components that can occur over time due to the chemical reactions within the fuel. This extends the lifespan of these parts and reduces the need for costly repairs. While emptying the tank requires a bit of effort, it’s a worthwhile practice that contributes to the longevity and reliability of your lawn mower.
How do I properly empty the gas tank of my lawn mower for storage?
The safest and most common method for emptying a lawn mower’s gas tank is to use a siphon pump. Position an approved gasoline container lower than the fuel tank, insert one end of the siphon hose into the tank, and the other end into the container. Use the pump to initiate the flow of gasoline, allowing the fuel to drain completely into the container. Dispose of the old gasoline responsibly according to local regulations.
Alternatively, if your lawn mower has a fuel shut-off valve, you can simply turn it off and run the engine until it stalls, burning off the remaining fuel in the carburetor. However, this method doesn’t completely empty the tank, so a small amount of fuel stabilizer may still be beneficial. Never attempt to empty the tank by tipping the lawn mower over, as this can be dangerous and could damage the engine.
If I choose to empty the gas tank, what should I do with the remaining gasoline?
Old or unused gasoline should be disposed of properly to prevent environmental contamination and potential hazards. Never pour gasoline down drains, into sewers, or onto the ground, as this can pollute water sources and soil. Instead, store the gasoline in a tightly sealed, approved container clearly labeled “Waste Gasoline.”
Contact your local waste management authority or recycling center for information on how to safely dispose of gasoline in your area. Many communities offer hazardous waste collection programs where you can drop off gasoline and other hazardous materials for proper disposal. Alternatively, some auto repair shops or service stations may accept used gasoline for recycling or disposal.
What other maintenance steps should I take when storing my lawn mower for the winter?
Besides addressing the fuel situation, several other maintenance steps are crucial for proper lawn mower storage. Clean the mower deck thoroughly to remove grass clippings and debris, which can corrode the metal over time. Sharpen or replace the mower blades to ensure optimal cutting performance next season.
Change the engine oil according to the manufacturer’s recommendations, as old oil can contain contaminants that can damage the engine during storage. Remove the spark plug, add a small amount of engine oil to the cylinder, and pull the starter cord a few times to coat the cylinder walls with oil, protecting them from rust. Finally, store the lawn mower in a dry, covered area to protect it from the elements.
Are there any specific types of lawn mowers where leaving gas in the tank is more acceptable?
Generally, the recommendations for storing lawn mowers with or without gasoline are consistent across most types, including gas-powered push mowers, self-propelled mowers, and riding mowers. However, the urgency may differ slightly based on the type of carburetor and fuel system design. Mowers with more complex fuel systems might be more susceptible to clogs from degraded gasoline.
While fuel stabilizer can mitigate the risks, it’s still generally best practice to either empty the tank or treat the fuel, regardless of the mower type. For professional-grade or commercial mowers that are used frequently throughout the year, the risk of fuel degradation is lower if the fuel is consumed relatively quickly. However, for seasonal storage, the same principles apply to all gas-powered lawn mowers.