Gasoline, the lifeblood of our lawn mowers, doesn’t last forever. Over time, it degrades, potentially leading to engine troubles. But before you resign yourself to draining and replacing that old fuel, let’s explore what, if anything, you can add to old gas to potentially revitalize it for your lawn mower.
Understanding Old Gasoline: Why Does Fuel Go Bad?
Gasoline is a complex blend of hydrocarbons. Its volatile nature is what allows it to ignite easily in your lawn mower’s engine. However, this volatility is also its Achilles’ heel.
Oxidation: When exposed to air, gasoline reacts with oxygen, leading to the formation of gum and varnish. These sticky substances can clog fuel lines, carburetors, and other engine components.
Evaporation: Lighter, more volatile components of gasoline evaporate over time, leaving behind heavier, less combustible hydrocarbons. This reduces the fuel’s octane rating and makes it harder to start the engine.
Water Absorption: Gasoline can absorb moisture from the air, especially if the fuel tank isn’t properly sealed. Water in the fuel system can cause corrosion and lead to poor combustion. Ethanol-blended gasoline is particularly susceptible to water absorption.
Phase Separation: Ethanol-blended gasoline can undergo phase separation when it absorbs too much water. The ethanol and water separate from the gasoline, forming a distinct layer at the bottom of the tank. This ethanol-water mixture is highly corrosive and can severely damage the engine.
The Potential Solutions: Additives for Reviving Old Gas
While there’s no magic elixir to completely restore old gasoline to its original state, certain fuel additives can help mitigate some of the negative effects of fuel degradation. The effectiveness of these additives depends on the severity of the fuel’s degradation.
Fuel Stabilizers: Prevention is Better Than Cure
Fuel stabilizers are primarily designed to prevent gasoline from going bad in the first place. They contain antioxidants that inhibit oxidation, metal deactivators that prevent corrosion, and detergents that keep fuel lines and carburetors clean.
How They Work: Fuel stabilizers work by slowing down the chemical processes that cause gasoline to degrade. They help maintain the fuel’s octane rating, prevent gum and varnish formation, and protect the fuel system from corrosion.
When to Use: The best time to add a fuel stabilizer is when you’re storing your lawn mower for an extended period, such as over the winter. Add the stabilizer to a full tank of fresh gasoline before putting the mower away. You can also add it to your gas can to keep your fuel fresh longer.
Limitations: Fuel stabilizers are most effective when used with fresh gasoline. They can help slow down the degradation of fuel that’s already slightly stale, but they won’t magically restore severely degraded gasoline.
Fuel System Cleaners: Cleaning Up the Mess
Fuel system cleaners are designed to remove deposits from fuel lines, carburetors, and fuel injectors. They contain detergents and solvents that dissolve gum, varnish, and carbon buildup.
How They Work: Fuel system cleaners work by loosening and dissolving deposits in the fuel system. These deposits are then burned away during engine operation.
When to Use: If your lawn mower is running rough, stalling, or hard to start, it may be due to deposits in the fuel system. Adding a fuel system cleaner to the gasoline can help clean out these deposits and improve engine performance.
Limitations: Fuel system cleaners can be effective at removing deposits, but they won’t restore the octane rating of old gasoline or prevent phase separation in ethanol-blended fuels.
Octane Boosters: A Temporary Boost?
Octane boosters are designed to increase the octane rating of gasoline. They contain additives that improve the fuel’s resistance to knocking and pinging.
How They Work: Octane boosters work by increasing the fuel’s ability to withstand compression without detonating prematurely. This can improve engine performance and fuel efficiency, especially in high-performance engines.
When to Use: If your lawn mower’s engine is knocking or pinging, it may be due to low-octane fuel. Adding an octane booster to the gasoline can help alleviate these symptoms.
Limitations: Octane boosters provide only a temporary fix. They don’t address the underlying problem of fuel degradation and won’t prevent gum and varnish formation or phase separation. The increase in octane is often minimal and may not be noticeable in a small engine like a lawn mower. Moreover, using an octane booster with severely degraded fuel will not restore its original properties.
Ethanol Stabilizers: Combating Ethanol’s Effects
Ethanol stabilizers are specifically designed to address the problems associated with ethanol-blended gasoline. They contain additives that prevent phase separation, protect the fuel system from corrosion, and help keep the fuel stable.
How They Work: Ethanol stabilizers work by preventing water absorption, inhibiting corrosion, and keeping the ethanol and gasoline mixed together.
When to Use: If you’re using ethanol-blended gasoline in your lawn mower, it’s a good idea to use an ethanol stabilizer, especially if you’re storing the mower for an extended period.
Limitations: Ethanol stabilizers are most effective when used with fresh ethanol-blended gasoline. They can help prevent phase separation and corrosion, but they won’t restore severely degraded fuel.
The Right Approach: Assessing Your Fuel and Making a Decision
Before you add anything to your old gasoline, it’s important to assess its condition.
Smell Test: Does the gasoline smell stale, sour, or varnished? This is a sign of degradation.
Visual Inspection: Is the gasoline cloudy, discolored, or does it contain sediment? This could indicate water contamination or phase separation.
How Old is it?: If the gasoline is more than a few months old, it’s likely degraded to some extent. Gasoline that is over a year old should generally be discarded.
Once you’ve assessed the condition of your gasoline, you can decide whether to add an additive or simply drain and replace the fuel.
Slightly Stale Fuel: If the gasoline is only slightly stale and doesn’t show signs of significant degradation, you may be able to revive it by adding a fuel stabilizer or fuel system cleaner. However, make sure to dilute it with fresh gasoline.
Severely Degraded Fuel: If the gasoline is severely degraded, cloudy, discolored, or smells bad, it’s best to drain and replace it. Adding an additive to severely degraded fuel is unlikely to improve its condition and could potentially damage your engine.
Ethanol-Blended Fuel with Phase Separation: If you suspect phase separation, drain the entire fuel system, including the carburetor, and refill it with fresh, ethanol-free gasoline or gasoline treated with an ethanol stabilizer.
Beyond Additives: Other Factors to Consider
Adding an additive to old gasoline is only one part of the equation. Other factors can also affect your lawn mower’s performance.
Air Filter: A dirty air filter can restrict airflow to the engine, leading to poor performance and fuel inefficiency. Clean or replace the air filter regularly.
Spark Plug: A fouled or worn spark plug can cause starting problems, misfires, and poor engine performance. Replace the spark plug as needed.
Carburetor: A dirty or clogged carburetor can cause a variety of problems, including starting difficulties, stalling, and rough running. Clean the carburetor periodically. Consider using a carburetor cleaner additive in fresh fuel to help maintain its cleanliness.
Fuel Filter: The fuel filter prevents debris from entering the carburetor. A clogged fuel filter will restrict fuel flow. Replace it regularly.
Best Practices for Storing Gasoline
Preventing gasoline from going bad in the first place is the best way to avoid the need for additives. Follow these best practices for storing gasoline:
Use a Proper Container: Store gasoline in a tightly sealed, approved container. Avoid using containers that are not specifically designed for gasoline storage.
Store in a Cool, Dry Place: Store gasoline in a cool, dry place away from direct sunlight and heat.
Add Fuel Stabilizer: Add a fuel stabilizer to the gasoline when you purchase it, especially if you plan to store it for an extended period.
Use Fresh Gasoline: Use the oldest gasoline first and avoid storing gasoline for more than a few months.
Consider Ethanol-Free Gasoline: If possible, use ethanol-free gasoline in your lawn mower. Ethanol-free gasoline is less susceptible to water absorption and phase separation.
The Final Verdict: Additives as a Supporting Role
While fuel additives can help mitigate some of the negative effects of old gasoline, they’re not a substitute for proper fuel storage and maintenance. If your gasoline is severely degraded, it’s always best to drain and replace it with fresh fuel. Additives can be a helpful supplement, especially when used preventatively or to address minor fuel degradation issues. By understanding the limitations of fuel additives and following best practices for fuel storage, you can keep your lawn mower running smoothly for years to come.
Can I just add new gas to old gas in my lawn mower and hope for the best?
Adding fresh gasoline to old gas in your lawn mower can sometimes work, especially if the old gas is only a few months old and the amount of fresh gas significantly outweighs the old. The idea is to dilute the stale gas and provide enough volatile hydrocarbons for proper combustion. However, it’s important to understand that the old gas has likely degraded, losing its lighter, more volatile components, and potentially forming gummy deposits that can clog the carburetor.
While dilution may provide temporary improvement, it doesn’t reverse the degradation process. You might experience rough starting, decreased engine performance, or even stalling if the mixture is still too poor. The best practice is always to drain and properly dispose of old gas, ensuring a clean fuel system and optimal performance from your lawn mower.
What are the signs that the gas in my lawn mower is too old?
Several telltale signs indicate that the gas in your lawn mower is past its prime. A common indicator is difficulty starting the engine, even after multiple attempts. This is because the lighter, more easily ignitable components of the gasoline have evaporated, making it harder to achieve the initial combustion needed for the engine to run.
Another sign is a noticeable decrease in engine performance, such as rough idling, sputtering, or a general lack of power when cutting grass. You might also observe unusual smoke coming from the exhaust or experience the engine stalling frequently. Furthermore, if the gas has a sour or varnished smell compared to fresh gasoline, it’s a strong indication that it has degraded significantly.
Is there anything I can add to old gas to make it usable again without draining it completely?
Fuel stabilizers are designed to help preserve gasoline and prevent it from degrading quickly. Adding a fuel stabilizer to old gas can sometimes help revive it, especially if the gas is only moderately stale and hasn’t formed significant gummy deposits. These stabilizers work by preventing oxidation and the breakdown of the fuel, which contributes to varnish formation and the loss of volatile components.
However, fuel stabilizers are most effective when added to fresh gasoline to prevent degradation in the first place. If the gas is severely degraded, adding a stabilizer might not be sufficient to restore it to its original quality. In such cases, draining the old gas and cleaning the fuel system is still the recommended course of action for optimal performance.
How long can I realistically expect gasoline to last in my lawn mower before it goes bad?
Unstabilized gasoline typically starts to degrade noticeably after about 30 days, losing its volatility and forming varnish-like deposits. After about 3-6 months, it can become difficult or impossible to start the engine, and performance will likely suffer significantly. The exact lifespan can vary depending on the quality of the gasoline, storage conditions (temperature, humidity), and the type of container used.
Adding a fuel stabilizer to gasoline can extend its shelf life considerably, often to 12 months or even longer. This is especially beneficial if you only use your lawn mower seasonally. Proper storage in a tightly sealed container in a cool, dry place away from direct sunlight is also crucial for maximizing the fuel’s longevity.
What kind of fuel stabilizer should I use for my lawn mower?
When selecting a fuel stabilizer for your lawn mower, look for products specifically designed for small engines and those that offer protection against ethanol-related problems. Ethanol, often added to gasoline, can attract moisture and cause corrosion in fuel systems, especially in older engines not designed for it. Choose a stabilizer that addresses these issues.
Read the product label carefully and follow the manufacturer’s instructions regarding the correct dosage. Overdosing won’t necessarily improve performance and could potentially cause problems. It’s also beneficial to choose a stabilizer from a reputable brand known for producing quality fuel additives.
What are the potential risks of using old or improperly treated gas in my lawn mower?
Using old or improperly treated gas in your lawn mower can lead to a range of problems, from poor engine performance to costly repairs. The degraded fuel can clog the carburetor jets and fuel lines, restricting fuel flow and causing starting difficulties, rough idling, and stalling. Over time, these deposits can harden and become difficult to remove, requiring professional cleaning or even carburetor replacement.
Furthermore, the ethanol in old gas can separate from the gasoline and attract water, leading to corrosion in the fuel system and damage to engine components. This water can also cause the engine to run lean, potentially overheating and causing internal damage. In severe cases, using old gas can even void your lawn mower’s warranty.
How should I properly dispose of old gasoline from my lawn mower?
Disposing of old gasoline responsibly is crucial to protect the environment and prevent potential hazards. Never pour old gasoline down the drain, into a storm sewer, or onto the ground, as this can contaminate water supplies and harm wildlife. Contact your local waste management authority or recycling center to inquire about hazardous waste disposal programs.
Many communities offer designated drop-off locations where you can safely dispose of old gasoline and other hazardous materials. Alternatively, some auto repair shops or gas stations may accept used gasoline for recycling. Always transport the gasoline in a tightly sealed, approved container and follow any specific instructions provided by the disposal facility.