As a lawn care specialist with years of experience in maintaining and servicing lawn equipment, I can provide you with a comprehensive answer to your question regarding whether it is bad to leave gas in your lawnmower over winter.

Firstly, it is essential to understand that gasoline is a volatile substance that can degrade over time. When gasoline is left in a lawnmower for an extended period, such as over the winter months, it can lead to several issues. One of the primary concerns is that the gasoline can become stale, which means that the additives that prevent the growth of bacteria and algae, as well as those that prevent rust and corrosion, can break down. This can result in the gasoline becoming thick and gummy, which can cause it to clog the fuel lines and gum up the carburetor.

The carburetor is a critical component of the lawnmower's engine. It is responsible for mixing the air and fuel in the correct proportions for combustion. When the gasoline becomes stale and gums up the carburetor, it can lead to poor performance, starting issues, and even engine damage. Moreover, the presence of water in the gasoline can exacerbate the problem by promoting rust and corrosion within the engine.

Another concern with leaving gasoline in a lawnmower over winter is the potential for rust. Rust can form on the metal parts of the engine and fuel system, which can lead to leaks and other mechanical issues. This is particularly problematic if the lawnmower is stored in a damp or humid environment.

To mitigate these risks, it is generally recommended to follow these steps:


1. Empty the Gas Tank: Before storing your lawnmower for the winter, it is advisable to empty the gas tank. This will minimize the amount of gasoline that can degrade and cause problems.


2. Add Fuel Stabilizer: If you decide to leave some gasoline in the tank, it is crucial to add a fuel stabilizer. A fuel stabilizer is a chemical additive that helps to prevent the gasoline from breaking down and becoming stale. It also helps to inhibit the growth of bacteria and algae and prevents rust and corrosion.


3. Run the Mower: After adding the fuel stabilizer, run the lawnmower for a few minutes to ensure that the stabilizer is distributed throughout the fuel system. This will help to protect all the components that come into contact with the gasoline.


4. Store Properly: Store the lawnmower in a dry and well-ventilated area to prevent the buildup of moisture that can lead to rust and corrosion.


5. Check the Gasoline: If you have leftover gasoline after emptying the tank, it is generally safe to use it in your car, provided it has not been mixed with oil. However, it is best to use it up within a few months to avoid any potential issues.

In conclusion, while it is possible to leave some gasoline in your lawnmower over winter, it is not the best practice. The risks of gasoline degradation, carburetor clogging, and rust formation outweigh the convenience of leaving it in the tank. By taking the necessary precautions, such as emptying the tank, adding a fuel stabilizer, and storing the mower properly, you can ensure that your lawnmower is ready to perform at its best when the warmer seasons return.

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Empty the gas tank. Unused gas left in a mower over the winter can get stale, gumming up the carburetor and inviting rust. First, add fuel stabilizer to the tank, then run the mower to distribute it through the system. ... (You can put this gas in your car, provided it hasn't been mixed with oil.)read more >>