Leaving gas in your lawn mower might seem like a minor detail, but it can actually have significant consequences for the performance and longevity of your machine. While the immediate convenience of not having to drain the fuel tank after each use is tempting, the potential problems it can create make it a habit worth reconsidering. This comprehensive guide delves into the science behind fuel degradation, explores the potential damages it can inflict, and offers practical advice on how to properly store your lawn mower for optimal performance and a long lifespan.
The Science of Fuel Degradation
Gasoline isn’t the stable, unchanging liquid we often assume it to be. It’s a complex mixture of hydrocarbons, and over time, it undergoes a process of degradation that can wreak havoc on your lawn mower’s engine. Understanding this process is key to appreciating why leaving gas in your mower is generally a bad idea.
The Breakdown of Gasoline
Gasoline begins to break down almost immediately after it’s refined. Several factors contribute to this deterioration, including oxidation, evaporation, and the absorption of moisture.
- Oxidation: Exposure to oxygen causes gasoline to oxidize, forming gum and varnish deposits. These sticky substances can clog fuel lines, carburetor jets, and other critical engine components.
- Evaporation: Lighter, more volatile components of gasoline evaporate over time, leaving behind heavier, less combustible residues. This reduces the fuel’s octane rating and makes it harder for the engine to start.
- Moisture Absorption: Gasoline is hygroscopic, meaning it readily absorbs moisture from the air. Water in the fuel tank can lead to corrosion and fuel-water separation, further hindering engine performance.
The Role of Ethanol
Most gasoline sold today contains ethanol, an alcohol-based additive designed to increase octane and reduce emissions. However, ethanol also accelerates fuel degradation and exacerbates some of the problems mentioned above.
- Ethanol’s Hygroscopic Nature: Ethanol attracts and absorbs even more moisture than gasoline alone. This increased water content promotes corrosion and fuel separation.
- Ethanol’s Corrosive Effects: Ethanol can corrode or dissolve rubber and plastic components in older fuel systems that weren’t designed to handle it.
The Damages of Stale Gasoline
Leaving stale gasoline in your lawn mower can lead to a variety of problems, ranging from minor inconveniences to major engine repairs. These issues can impact the mower’s performance, lifespan, and overall reliability.
Starting Problems
One of the most common symptoms of stale gasoline is difficulty starting the engine. The degraded fuel may not ignite properly, or the gum and varnish deposits may clog the carburetor, preventing fuel from reaching the combustion chamber. A mower that refuses to start is a clear sign that the fuel needs to be addressed.
Poor Engine Performance
Even if the engine does start, stale gasoline can lead to poor performance. The mower may run rough, lack power, or stall frequently. These issues are often caused by incomplete combustion or fuel starvation due to clogged fuel lines or carburetor jets.
Carburetor Clogging
The carburetor is a crucial component that mixes air and fuel in the correct proportions for combustion. Stale gasoline can clog the tiny passages within the carburetor, disrupting this delicate balance and leading to engine problems. Carburetor cleaning or replacement may be necessary if the fuel has significantly degraded.
Fuel Line Deterioration
Ethanol in gasoline can degrade rubber and plastic fuel lines, causing them to crack, leak, or become brittle. These leaks can be a fire hazard and can also lead to fuel starvation.
Corrosion
Water in the fuel tank can cause corrosion of metal components, such as the fuel tank itself, the fuel pump, and the carburetor. This corrosion can lead to fuel leaks, engine damage, and costly repairs.
Best Practices for Lawn Mower Fuel Storage
To avoid the problems associated with stale gasoline, it’s essential to adopt proper fuel storage practices. These practices will help keep your fuel fresh and your lawn mower running smoothly.
Fuel Stabilizers
Fuel stabilizers are additives that can help prevent gasoline from degrading over time. They work by inhibiting oxidation, preventing the formation of gum and varnish, and protecting against corrosion.
- How to Use Fuel Stabilizers: Add the recommended amount of fuel stabilizer to your gasoline can according to the manufacturer’s instructions. Mix the stabilizer thoroughly with the fuel before adding it to your lawn mower’s fuel tank.
- When to Use Fuel Stabilizers: Use fuel stabilizers whenever you plan to store your lawn mower for more than a month, or whenever you’re using gasoline that may be several months old.
Draining the Fuel Tank
Draining the fuel tank is another effective way to prevent fuel degradation. This removes the gasoline from the mower’s fuel system, preventing it from oxidizing and forming deposits.
- How to Drain the Fuel Tank: Disconnect the spark plug wire for safety. Locate the fuel shut-off valve (if equipped) and close it. Disconnect the fuel line from the carburetor and drain the fuel into a suitable container. You can also siphon the fuel out of the tank using a siphon pump.
- When to Drain the Fuel Tank: Drain the fuel tank whenever you plan to store your lawn mower for an extended period, such as over the winter months.
Using Fresh Gasoline
The best way to avoid problems with stale gasoline is to use fresh gasoline whenever possible. Buy only the amount of gasoline you need for a month or two and store it in a tightly sealed container in a cool, dry place. Avoid using gasoline that is more than six months old.
Long-Term Storage Solutions
Preparing your lawn mower for long-term storage requires a few extra steps to ensure it’s ready to go when spring arrives. These steps go beyond just dealing with the fuel and address other critical components.
Oil Change
Before storing your lawn mower for the winter, it’s a good idea to change the oil. Used oil contains contaminants that can corrode engine components over time. Fresh oil will protect the engine during storage.
Spark Plug
Remove the spark plug and inspect it for wear or damage. If necessary, replace the spark plug with a new one. Pour a small amount of engine oil into the spark plug hole and pull the starter cord a few times to coat the cylinder walls with oil. This will help prevent corrosion.
Cleaning the Mower
Thoroughly clean the mower deck and engine to remove any grass clippings, dirt, or debris. These materials can trap moisture and lead to corrosion. Use a brush or scraper to remove stubborn debris, and then wipe down the mower with a damp cloth.
Storage Location
Store your lawn mower in a dry, protected location, such as a garage or shed. Avoid storing it outdoors, where it will be exposed to the elements. Cover the mower with a tarp or cover to protect it from dust and moisture.
Addressing Existing Fuel Problems
If you suspect that your lawn mower is suffering from stale gasoline-related problems, there are several steps you can take to address the issue. Sometimes, a simple solution can revive your mower, but other times, more extensive repairs may be needed.
Draining and Replacing the Fuel
The first step is to drain the old fuel from the tank and replace it with fresh gasoline. Add a fuel stabilizer to the new fuel to help prevent future degradation. This simple step can often resolve minor starting or performance issues.
Cleaning the Carburetor
If the engine still doesn’t start or runs poorly after replacing the fuel, the carburetor may be clogged. You can try cleaning the carburetor yourself using carburetor cleaner, or you can take it to a professional for cleaning or rebuilding. A clean carburetor is essential for proper engine performance.
Replacing Fuel Lines and Filters
Inspect the fuel lines and fuel filter for signs of deterioration or clogging. Replace any damaged or clogged components. This will ensure that fuel can flow freely to the engine.
Professional Service
If you’re not comfortable performing these repairs yourself, or if the problems persist, it’s best to take your lawn mower to a qualified service technician. They can diagnose the problem and perform the necessary repairs to get your mower running smoothly again.
Leaving gas in your lawn mower might seem convenient in the short term, but it can lead to a host of problems in the long run. By understanding the science of fuel degradation and following proper storage practices, you can keep your lawn mower running smoothly and avoid costly repairs. Prioritize regular maintenance and proactive care to extend the life of your lawn mower and enjoy a well-manicured lawn for years to come.
Is it OK to Leave Gas in a Lawn Mower Over Winter?
Leaving gasoline in your lawn mower’s fuel tank over the winter months is generally not recommended. Gasoline, especially modern blends containing ethanol, can degrade over time. This degradation can lead to the formation of gum and varnish deposits that can clog the carburetor and fuel lines, making it difficult, if not impossible, to start the mower in the spring.
Furthermore, ethanol can attract moisture, leading to phase separation in the fuel. This means the ethanol and water separate from the gasoline, creating a corrosive layer that can damage internal engine components. Draining the fuel tank or adding a fuel stabilizer is a far better option for long-term storage to prevent these issues and ensure your mower starts smoothly when you need it again.
What Type of Gas is Best for My Lawn Mower?
The best type of gas for your lawn mower is generally fresh, unleaded gasoline with an octane rating of 87 or higher. Check your owner’s manual for specific recommendations, as some manufacturers may have additional requirements or preferences. Using the correct octane level will ensure optimal engine performance and longevity.
However, it’s crucial to avoid gasoline containing more than 10% ethanol (E10). Ethanol can damage small engines, especially older models, by corroding rubber and plastic components. Ideally, use ethanol-free gasoline if available, or opt for a fuel stabilizer designed to counteract the negative effects of ethanol when storing the mower.
How Often Should I Change the Gas in My Lawn Mower?
You should ideally change the gas in your lawn mower whenever you suspect it is old or has been sitting for an extended period. Generally, gasoline starts to degrade after about 30 days, especially when exposed to air and temperature fluctuations. If the mower hasn’t been used for several weeks or months, it’s best to drain the old gas and replace it with fresh fuel.
For optimal performance, it’s a good practice to drain the fuel tank before storing the mower for the winter or any prolonged period of inactivity. Fresh gasoline ensures easier starting and reduces the risk of engine problems caused by stale or contaminated fuel. Always dispose of old gasoline properly at a designated recycling center or hazardous waste facility.
Can I Use Fuel Stabilizer to Preserve Gas in My Lawn Mower?
Yes, using a fuel stabilizer is a highly recommended practice to preserve gasoline in your lawn mower, especially during periods of storage. Fuel stabilizers work by preventing the degradation of gasoline, inhibiting the formation of gum and varnish, and protecting against ethanol-related issues like moisture absorption and phase separation. Adding a fuel stabilizer to the gas tank before storage can significantly extend the fuel’s lifespan and maintain its quality.
To use a fuel stabilizer effectively, follow the manufacturer’s instructions regarding the correct ratio of stabilizer to gasoline. Pour the stabilizer into the gas tank and then run the engine for a few minutes to ensure the treated fuel circulates throughout the fuel system. This will help protect the carburetor, fuel lines, and other components from corrosion and deposits.
What are the Signs of Bad Gas in a Lawn Mower?
Several signs can indicate that the gas in your lawn mower has gone bad. One common symptom is difficulty starting the engine, or the engine may start but run rough or stall frequently. Bad gas can also cause the engine to lack power or exhibit poor performance, even after it has warmed up.
Another indicator is the presence of a varnish-like smell emanating from the fuel tank or carburetor. You might also observe visible deposits or discoloration in the gasoline itself. If you suspect your mower is running on bad gas, it’s best to drain the tank, clean the fuel system if necessary, and refill with fresh fuel.
How Do I Properly Drain the Gas from My Lawn Mower?
Draining the gas from your lawn mower is a relatively straightforward process, but it requires caution to avoid spills and potential hazards. First, ensure the engine is cool and located in a well-ventilated area away from any open flames or sources of ignition. Disconnect the spark plug wire to prevent accidental starting.
Next, locate the fuel shut-off valve (if equipped) and close it. Place a suitable container beneath the carburetor to catch the draining fuel. Loosen the drain screw on the carburetor, or carefully detach the fuel line from the carburetor, allowing the gas to flow into the container. Once the tank is empty, tighten the drain screw or reattach the fuel line securely. Dispose of the old gasoline properly at a designated recycling center or hazardous waste facility.
What Happens if I Ignore Bad Gas in My Lawn Mower?
Ignoring bad gas in your lawn mower can lead to a range of engine problems and potentially costly repairs. As the gas degrades, it forms gum and varnish deposits that can clog the carburetor jets and fuel lines, restricting fuel flow and causing the engine to run poorly or fail to start altogether.
Furthermore, the ethanol in old gasoline can attract moisture, leading to corrosion of internal engine components and damage to rubber and plastic parts. In severe cases, ignoring bad gas can necessitate carburetor cleaning or replacement, fuel line repairs, and even engine rebuilds. Regularly using fresh fuel and properly storing your lawn mower can prevent these issues and extend the life of your equipment.