Can You Put Mixed Gas in a Lawn Mower? Exploring the Pros and Cons


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Can you put mixed gas in a lawn mower? This is a question that many lawn mower owners ask themselves. The answer, however, is not as straightforward as one would hope. With so much conflicting information available online and offline, it's easy to become overwhelmed and confused.

Mixed gas refers to the fuel mixture of gasoline and oil used in two-stroke engines like those found in some types of lawn mowers. While it may seem like a simple solution to use mixed gas instead of regular gasoline for your lawnmower, there are several factors that must be considered before making the switch. Some people swear by using mixed gas for their lawnmowers while others discourage it altogether.

In this article, we'll dive deeper into the topic of whether or not you can put mixed gas in your lawn mower without causing damage or other problems. We'll explore both sides of the argument and provide you with all the information you need to make an informed decision regarding what type of fuel is best for your machine. So read on!

Can You Put Mixed Gas in a Lawn Mower?

Lawn mowers are essential tools for maintaining a well-manicured lawn. They come in different types, but they all have one thing in common – the need for fuel to power their engines. One common question that comes up when it comes to fueling your lawn mower is whether you can put mixed gas in it.

What is Mixed Gas?

Mixed gas, also known as two-stroke oil or 2-cycle oil, is gasoline that has been blended with engine oil. It's used to power two-stroke engines commonly found on boats, chainsaws, and other handheld power tools.

The ratio of gasoline to engine oil varies depending on the manufacturer's recommendations or the type of equipment you're using. Most manufacturers recommend using a 50:1 ratio (gasoline:oil), while some others recommend lower ratios like 40:1 or higher ones like 100:1.

Can You Use Mixed Gas in Your Lawn Mower?

Now that we know what mixed gas is let's answer the question – can you use mixed gas in your lawn mower? The short answer is no; it's not recommended to use mixed gas in your lawnmower unless specified by its manufacturer.

Most lawnmowers have four-stroke engines that require pure gasoline without any added oils. Adding two-cycle motor oil could damage the engine and cause serious problems with performance and durability over time.

In addition, most lawnmower engines require unleaded regular gasoline with an octane rating of at least 87 according to Briggs & Stratton Corporation – an American Fortune 1000 manufacturer of internal combustion engines for outdoor power equipment.

Why Shouldn't You Use Mixed Gas In Your Lawn Mower

Using mixed-gas could cause various issues such as:

  • Clogging Your Carburetor
    Mixing two-cycle motor oil into regular unleaded fuel will create a gummy, sticky substance that can clog your carburetor’s small fuel passages and jets. This can cause poor performance and make it difficult to start your lawnmower.

  • Engine Knocking
    Lawnmower engines are not designed to run on mixed gas and adding it could cause knocking sounds in the engine. This is because two-stroke oil burns differently than regular gasoline, causing a detonation or pre-ignition that damages the engine over time.

  • Decreased Performance
    Mixed-gas has less energy per gallon compared to pure gasoline, which means your mower may not operate at peak performance even if you get it started with mixed-gas.

Benefits of Using Pure Gasoline In Your Lawn Mower

Using pure gasoline has several benefits for your lawn mower:

  1. Longer Engine Life
    Pure gasoline reduces carbon build-up in the combustion chamber exhaust port, spark plug fouling, ring sticking during cold weather starts leading to longer engine life.

  2. Increased Fuel Efficiency
    Pure unleaded gas offers greater fuel efficiency rates resulting in better lawn mowing experience by providing optimal usage of fuel per acre as compared with mixed gas whose energy density limits its use and capability leading t overall decreased quality of work done using this type of fuel

  3. Reduced Emissions
    Since pure unleaded gas doesn't contain any oils or additives like two-cycle motor oil does thus burning cleaner than other fuels this helps reduce emissions from lawnmowers promoting environmentally-friendly practices when operating outdoor power equipment.

Tips for Fueling Your Lawn Mower

Here are some tips for safely filling up your lawn mower's tank:

  1. Use fresh gasoline: Stale or contaminated gas can damage the carburetor so always use fresh petrol.
  2. Check manufacturer recommendations: Read through the owner's manual before putting fuel into any new equipment as manufacturers have different requirements regarding what type of petrol/oil mixture should be used; they usually recommend using pure gas.
  3. Use appropriate fuel containers: Always store petrol in a sealed container designated for fuel use only, and keep it out of reach from children or pets to avoid accidents.
  4. Fill up in a well-ventilated area: Gasoline fumes are flammable so make sure you fill the tank in an open, well-ventilated area away from any ignition sources like cigarettes or sparks.


In conclusion, you should never put mixed-gas into your lawn mower unless specified by its manufacturer as it could cause damage to both the engine and other components leading to decreased performance overall. Instead, always use fresh unleaded gasoline with an octane rating of at least 87 per Briggs & Stratton Corporation's recommendations; this will help increase your lawnmower's lifespan while also promoting cleaner emissions and better fuel efficiency rates overall when operating outdoor power equipment.


Can you put mixed gas in a lawn mower?

It is not recommended to use mixed gas in your lawnmower since it can cause damage to the engine and other components. Mixed gas usually contains fuel stabilizers, ethanol, or octane boosters that may be harmful to small engines like those found in lawnmowers. Additionally, using mixed gas can also void your warranty.

Instead of using mixed gas, it is best to use regular unleaded gasoline with an octane rating of 87 or higher. You should avoid using gasoline that contains more than 10% ethanol since ethanol can attract moisture and lead to corrosion within the fuel system.

When filling up your lawnmower’s tank, make sure you use clean and fresh gasoline free from water or debris. It is also advisable to add a fuel stabilizer especially if you plan on storing the mower for an extended period.

What happens if I put mixed gas in my lawn mower?

Putting mixed gas into your lawn mower may result in several problems including starting issues, rough idling or stalling while mowing. This is because engines require specific ratios of air/fuel mixture for optimal performance; adding additional chemicals found within the mix could throw off this balance leading poor performance at best and permanent engine damage at worst

The oil-fuel mixture used by two-stroke engines such as those on chainsaws differs from that used by four-stroke mowers meaning they cannot be interchanged without causing harm

In some instances where only a small amount of mixing has occurred then there may be no immediate effects; however over time these symptoms will become increasingly pronounced as any damage becomes more severe

How do I know whether my lawn mower takes two-cycle or four-cycle oil?

Most newer model lawnmowers take four-cycle oil which does not require mixing with gasoline but instead goes directly into its own reservoir located under the hood near any valves present thereon

If unsure, consult the manufacturers' manual or website for more specific information on your mower. Additionally, it is possible to determine which type of oil a lawnmower requires through an inspection of its engine and fueling system.

What can I do if I accidentally put mixed gas in my lawn mower?

If you have mistakenly added mixed gas into your lawnmower tank, it's best to drain the entire fuel system thoroughly as soon as possible. This includes removing any remaining gasoline from the carburetor bowl and flushing out any excess mix from other parts like lines or filters.

If you are unsure about how to flush out your lawnmower's fuel system after adding mixed gas, consider taking it to a professional mechanic who will be able to help you properly clean and repair any damage that may have been caused by this mistake.

Can using mixed gas cause permanent damage?

Yes, using mixed gas in your lawn mower can lead to permanent damage such as engine failure or seizures due to incorrect air/fuel ratios leading too lean conditions causing overheating; damange caused by ethanol corrosion buildup within the combustion chamber; piston ring breakage because of detonation knocking leading serious engine issues overall.

In addition these damages could result in expensive repairs that may not be covered under warranty since they are likely considered as owner negligence rather than manufacturer defect


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