Old gasoline is the bane of many lawn mower owners. You pull your mower out after winter, eager to get your lawn looking sharp, only to be met with sputtering, refusing to start, or running poorly. The culprit? Often, it’s the old gas sitting in the tank. But will a lawn mower actually start with old gas? And if it does, is it safe to use? Let’s dive deep into the science behind gasoline degradation and explore practical solutions to common fuel-related lawn mower problems.
Understanding Gasoline Degradation
Gasoline isn’t a static substance. It’s a complex mixture of hydrocarbons that are susceptible to degradation over time. The key factors that contribute to this breakdown are oxidation, evaporation, and the absorption of moisture. These processes transform gasoline into something far less efficient and potentially damaging to your lawn mower engine.
Oxidation: The Rust of Fuel
Oxidation is a chemical reaction between gasoline and oxygen. This process causes the fuel to break down and form varnish and gum-like substances. These sticky residues can clog fuel lines, carburetors, and other critical engine components. Think of it like rust forming inside your fuel system. Oxidation is accelerated by heat and sunlight, which is why storing gasoline properly is crucial.
Evaporation: Losing the Volatile Components
Gasoline is designed with specific volatile components that allow it to ignite easily in the engine. Over time, these lighter components evaporate, leaving behind heavier, less flammable substances. This leads to a reduction in octane levels, making the fuel less efficient and potentially causing knocking or pinging in the engine. The less volatile fuel is, the harder it will be to start your mower, especially in colder conditions.
Moisture Absorption: Water in the Fuel
Gasoline can absorb moisture from the air, particularly in humid environments. Water in the fuel tank can lead to several problems. First, it can cause corrosion in the fuel system. Second, it can separate from the gasoline, forming a layer of water at the bottom of the tank. This water can then be drawn into the engine, causing it to stall or misfire. Ethanol-blended gasoline (E10) is particularly susceptible to water absorption, which makes it even more critical to store it properly.
The Impact of Old Gas on Your Lawn Mower
The degradation of gasoline directly impacts your lawn mower’s performance and longevity. The severity of the impact depends on the age of the gas, the storage conditions, and the type of engine.
Starting Problems: The Most Common Symptom
The most common problem associated with old gas is difficulty starting the lawn mower. The degraded fuel may not ignite properly, making it hard to get the engine running. You might find yourself pulling the starter cord repeatedly without any success, or the engine might sputter and die shortly after starting. This is because the volatile components needed for ignition have evaporated.
Poor Engine Performance: Reduced Power and Efficiency
Even if the lawn mower does start with old gas, it may run poorly. You might notice a decrease in power, making it difficult to cut through thick grass. The engine might also run rough, misfire, or stall frequently. The degraded fuel doesn’t burn as efficiently, leading to incomplete combustion and reduced energy output.
Engine Damage: A Long-Term Concern
Using old gas can lead to long-term engine damage. The varnish and gum deposits can clog fuel lines and carburetor jets, restricting fuel flow and causing the engine to run lean. A lean-running engine operates at higher temperatures, which can damage pistons, valves, and other critical components. Ignoring the problem can lead to costly repairs or even engine replacement.
How Long Does Gasoline Last?
The lifespan of gasoline depends on several factors, including the type of gasoline, storage conditions, and the presence of fuel stabilizers.
Unstabilized Gasoline: A Short Shelf Life
Unstabilized gasoline typically has a shelf life of 3 to 6 months. After this period, it begins to degrade noticeably, leading to the problems described above. The higher the ethanol content, the shorter the shelf life.
Stabilized Gasoline: Extending the Lifespan
Adding a fuel stabilizer to gasoline can significantly extend its shelf life. Fuel stabilizers contain antioxidants and other additives that prevent oxidation and keep the fuel fresh for longer. With a fuel stabilizer, gasoline can last for up to 12 months or even longer.
Storage Conditions: A Key Factor
Proper storage is crucial for maximizing the lifespan of gasoline. Store gasoline in a clean, airtight container in a cool, dry place away from direct sunlight. A sealed container prevents evaporation and minimizes moisture absorption.
What to Do with Old Gas
If you suspect that the gas in your lawn mower is old, don’t panic. You have several options.
Dispose of it Properly: Environmental Responsibility
The best option is to dispose of the old gas properly. Contact your local waste management authority for information on how to dispose of gasoline safely and legally. Never pour gasoline down the drain or onto the ground.
Use it in a Different Application (With Caution)
In some cases, you might be able to use the old gas in a less demanding application, such as mixing it with fresh gasoline in your car’s fuel tank. However, this should be done with caution and only if the gas is only slightly degraded. Diluting old gas with fresh gas can help mitigate the negative effects.
Revive it with Additives: A Risky Approach
There are fuel additives on the market that claim to revive old gas. However, these additives are not always effective, and they may not fully restore the fuel’s original properties. Using these additives is a risky approach and may not be worth the potential damage to your engine.
Preventing Old Gas Problems
The best way to avoid problems with old gas is to prevent it from becoming old in the first place. Here are some tips for keeping your gasoline fresh.
Use Fuel Stabilizer: The First Line of Defense
Always add a fuel stabilizer to gasoline when storing it for more than a month. This will help prevent oxidation and keep the fuel fresh for longer. Follow the manufacturer’s instructions for proper dosage.
Buy Only What You Need: Minimize Waste
Avoid buying large quantities of gasoline that you won’t use within a few months. This will minimize the amount of gasoline that sits unused and potentially degrades. Only purchase the amount you anticipate using within a reasonable timeframe.
Store Gasoline Properly: The Key to Longevity
Store gasoline in a clean, airtight container in a cool, dry place away from direct sunlight. This will help prevent evaporation and minimize moisture absorption. A sealed metal or plastic container specifically designed for gasoline is ideal.
Empty the Tank Before Storage: A Proactive Approach
Before storing your lawn mower for the winter, empty the fuel tank completely. This will prevent the gasoline from sitting in the tank and degrading over the off-season. This is the most effective way to prevent old gas problems.
Troubleshooting Lawn Mower Starting Problems
If your lawn mower won’t start, even after following the preventive measures, here are some troubleshooting steps.
Check the Spark Plug: A Common Culprit
A dirty or fouled spark plug can prevent the engine from starting. Remove the spark plug and inspect it for signs of damage or carbon buildup. Clean or replace the spark plug as needed. A healthy spark plug is essential for proper ignition.
Clean the Air Filter: Ensuring Proper Airflow
A clogged air filter can restrict airflow to the engine, making it difficult to start. Remove the air filter and clean or replace it as needed. A clean air filter ensures optimal engine performance.
Inspect the Fuel Lines: Checking for Blockages
Fuel lines can become clogged with debris or deteriorated fuel. Inspect the fuel lines for any signs of blockage or damage. Clean or replace the fuel lines as needed. Clear fuel lines are crucial for proper fuel delivery.
Clean the Carburetor: A More Involved Process
The carburetor is responsible for mixing air and fuel in the proper ratio. A dirty or clogged carburetor can prevent the engine from starting. Cleaning the carburetor can be a more involved process, but it’s often necessary to restore proper engine function. Professional carburetor cleaning may be required in severe cases.
Ethanol and Lawn Mowers: A Problematic Combination
Ethanol-blended gasoline (E10) is common at most gas stations. While it might be suitable for cars, it poses several problems for lawn mowers.
Water Absorption: A Major Concern
Ethanol attracts water, which can lead to phase separation in the fuel tank. This means that the water separates from the gasoline, forming a layer at the bottom of the tank. This water can then be drawn into the engine, causing it to stall or misfire. Ethanol’s hygroscopic nature is a significant challenge for small engines.
Corrosion: Damaging Engine Components
Ethanol can corrode rubber and plastic components in the fuel system, leading to leaks and other problems. This is particularly problematic for older lawn mowers that were not designed to run on ethanol-blended gasoline. Ethanol’s corrosive properties can shorten the lifespan of fuel system components.
Alternative Fuels: A Potential Solution
Consider using ethanol-free gasoline in your lawn mower. Ethanol-free gasoline is less prone to water absorption and corrosion, making it a better choice for small engines. Ethanol-free gasoline is often available at marinas or specialty fuel retailers.
Navigating the world of lawn mower fuel can be challenging, but understanding the science behind gasoline degradation and taking proactive steps to prevent old gas problems will ensure your mower starts reliably and runs smoothly for years to come. By using fuel stabilizers, storing gasoline properly, and troubleshooting common starting problems, you can keep your lawn looking its best without the frustration of dealing with old gas.
FAQ 1: How old is too old when it comes to gasoline for a lawn mower?
Gasoline starts to degrade and lose its combustibility as it ages. Generally, gasoline can start to go bad after only 30 days, especially if stored improperly. After 3 to 6 months, untreated gasoline can become noticeably stale, resulting in starting difficulties or poor engine performance in your lawn mower.
Several factors influence how quickly gasoline degrades, including temperature fluctuations and exposure to air and moisture. Storing gasoline in a tightly sealed container in a cool, dark place can help prolong its lifespan. However, even with proper storage, it’s wise to avoid using gasoline that’s been sitting unused for more than 6 months.
FAQ 2: What happens to gasoline as it ages and why does that affect my lawn mower?
As gasoline ages, it undergoes a process called oxidation, which leads to the formation of gum and varnish deposits. These deposits can clog the carburetor and fuel lines in your lawn mower, restricting fuel flow and making it difficult or impossible to start the engine. The lighter, more volatile components of the gasoline also evaporate over time, reducing its octane rating and ability to ignite properly.
This degradation results in several issues for your lawn mower. Starting the engine becomes increasingly challenging, the engine may run rough or stall frequently, and overall performance will be diminished. In severe cases, using old gasoline can cause permanent damage to engine components, leading to costly repairs.
FAQ 3: Can I try to start my lawn mower with old gas, or is it better to just replace it immediately?
While tempting to try starting your lawn mower with old gas, it’s generally better to replace it immediately. Attempting to start the mower with degraded fuel can exacerbate existing problems. The gummy residues from old gasoline can further clog the fuel system, making it more difficult to clean and repair later.
Starting with fresh fuel ensures optimal engine performance and minimizes the risk of damage. It’s a simple step that can save you time, frustration, and potential repair costs in the long run. Drain the old gas and dispose of it properly before adding fresh gasoline to the tank.
FAQ 4: How can I properly dispose of old gasoline?
Disposing of old gasoline responsibly is important to protect the environment and prevent hazards. Never pour old gasoline down drains, onto the ground, or into sewers. These actions can contaminate water sources and pose a fire risk.
Contact your local waste management facility or environmental agency to inquire about proper disposal methods. Many communities offer hazardous waste collection programs or designated drop-off locations for gasoline and other fuels. Some auto repair shops or recycling centers may also accept old gasoline for recycling.
FAQ 5: What are some signs that the gasoline in my lawn mower is too old to use?
Several signs indicate that the gasoline in your lawn mower is too old to use. One of the most obvious signs is a noticeable change in the gasoline’s color and odor. Old gasoline may appear darker, cloudier, or have a sour or varnish-like smell compared to fresh gasoline.
Additionally, if your lawn mower is difficult to start, runs roughly, stalls frequently, or lacks power, it could be due to stale gasoline. Visual inspection of the fuel tank and carburetor may reveal gummy deposits or residue, further confirming the gasoline’s degradation.
FAQ 6: What is gasoline stabilizer and how does it help extend the life of gasoline for my lawn mower?
Gasoline stabilizer is an additive that helps prevent gasoline from degrading over time. It works by inhibiting oxidation and preventing the formation of gum and varnish deposits, which are the primary causes of stale gasoline. Stabilizers also help to maintain the gasoline’s octane rating and prevent water absorption.
By adding gasoline stabilizer to your fuel, you can extend its lifespan for several months or even a year, depending on the product and storage conditions. This is particularly beneficial for seasonal equipment like lawn mowers that may sit unused for extended periods. Follow the manufacturer’s instructions for the correct dosage and add the stabilizer when you purchase the gasoline.
FAQ 7: If I drain old gas from my lawn mower, do I need to clean the carburetor?
Draining old gas is a good first step, but it might not be enough if the gasoline has already left deposits in the carburetor. The old fuel’s residue can clog the small jets and passages within the carburetor, continuing to cause starting and running issues even with fresh gasoline.
Therefore, cleaning the carburetor is often necessary after draining old gas, especially if you suspect significant degradation. You can use a carburetor cleaner spray to dissolve deposits or, for more stubborn cases, disassemble the carburetor for a thorough cleaning. Consulting your lawn mower’s manual or a qualified mechanic is recommended for complex cleaning procedures.