While most push mowers manufactured today use 4-cycle (4-stage) engines, there are still many 2-cycle (2-stage) engines being used.

These engines do not work the same way and require different types of fuel. Using the wrong fuel in your push mower can cause fuel system issues and engine damage.

A push mower requires unleaded gasoline with a minimum octane rating of 87 and a maximum ethanol content of 10%. A 4-cycle push mower requires gasoline. A 2-cycle push mower requires a gasoline and oil mix. Using straight gasoline in a 2-cycle push mower will damage the engine.

Follow all safety precautions listed in your owner’s manual before working on your push mower. Make sure you are in a well-ventilated area when handling fuel. Keep fuel away from combustible products and extreme heat.

Choose the Right Gasoline for a Push Mower

It is best for your push mower to use fresh gasoline with low ethanol content. A fuel stabilizer should be added to fuels that are not consumed quickly.

Low Ethanol Content

Ethanol, an alternative fuel used in gasoline today, can cause problems in the small engines used on push mowers. Ethanol attracts moisture from the air which is corrosive to the fuel system.

In addition, fuel and water will separate from gasoline over time. This mixture will leave behind gummy deposits that can create fuel restrictions. It is very harmful to the engine when this mixture separates from the gas and runs through the engine.

Always choose low-ethanol gasoline that contains no more than 10% ethanol. The lower the ethanol level, the better. More and more fuels with ethanol are being sold at the local fuel stations.

Never use fuels sold as E15, E30, or E85. These fuels contain up to 15%, 30%, and 85% ethanol.

Use Fresh Gasoline

Gasoline can begin breaking down as soon as 30 days after purchase. It’s best to purchase the amount of fuel that can be used within 30 days to reduce damage to the push mower from fuel.

If you are unable to use the gasoline you purchased within this time, add a fuel additive to stabilize it so it lasts a little longer without breaking down.

Add a Fuel Stabilizer

I like to add Sea Foam Motor Treatment, a fuel additive to stabilize fuel, to every tank of gas. Sea Foam not only stabilizes gas, but it also cleans the fuel system and reduces moisture. It helps minimize problems that can develop from running old fuel.

Read more about using Sea Foam in, “Why Use Sea Foam Fuel Additive in a Lawn Mower“.

Ethanol-Free Fuel

Ethanol-free fuels are always best to run in your lawn mower, but it is a more expensive fuel choice. Ethanol-free fuel can be bought at some fuel stations often sold as recreation fuel or REC-90.

It can also be bought in canisters as a convenient option to store on the shelf in your storage shed or garage.

• 2-Cycle 50:1 Premix
• 2-Cycle 40:1 Premix
• 4-Cycle Fuel

Identify the Type of Engine on Your Mower: 2-Cycle or 4-Cycle Engine

How to identify a 2-cycle or 4-cycle engine:

• Fuel Cap: An original 2-cycle fuel cap will have the gas-to-oil mix ratio listed on the cap (32:1, 40:1, or 50:1) or it will show fuel and oil can on the cap.
• Number of Fill Ports: A 2-cycle engine will have one fill port for a gas-to-oil mix. A 4-cycle engine will have 2 fill ports. There will be one for engine oil and one for gas.
• Operator’s Manual: The manual that came with your push mower will list whether you need to use a mixed gas and oil mixture or straight gas.

Gas to Use for a 4-Cycle Push Mower or Self-Propelled Mower

Push mowers with 4-cycle engines require unleaded gasoline with a minimum octane rating of 87 and a maximum ethanol content of 10%.

Stay away from all gasoline with more than 10% ethanol like those sold at the fuel stations as E15, E35, and E85 fuels. These fuels contain up to 15%, 35%, and 85% ethanol respectively.

Gas and Oil Mix for a 2-Cycle Push Mower or Self-Propelled Mower

2-Cycle Gas and Oil Mix in a Push Mower or Self-Propelled Mower

Don’t mistakenly add straight gas to a 2-cycle push mower. If you do this and start your mower, it will most likely shut off and seize up. This is because a 2-cycle engine burns an oil and fuel mix.

Without the oil mixed with gas, the engine doesn’t get the lubrication it requires to run. Running straight gas will ruin the engine.

Push mowers with 2-cycle engines require gas and oil mixed at a ratio of 32:1, 40:1, or 50:1. For example, 50:1 mix equals 50 parts gasoline to 1 part oil.

The mix your mower requires varies by manufacturer. You can find the correct ratio in your operator’s manual. You may also find it located on the fuel cap.

When creating this mix for a 2-cycle engine, use unleaded gasoline with a minimum octane rating of 87 and maximum ethanol content of 10%. Add a 2-cycle premium oil that is ISO-L-EGD and JASO M345 FD certified.

How to Mix Gas and Oil for a 2-Cycle Push Mower:

• Use the chart below to determine how much fuel mix to prepare.
• Remove the cap from an approved gas can. Add unleaded fuel (minimum 89 octane rating & maximum 10% ethanol content) to a gas can.
• Using the chart for ounces of oil required, add the 2-cycle oil to the gas can.
• Replace the cap.
• Gently shake the fuel and oil until they are mixed.
• Add to the push mower’s fuel tank.

You can use the manufacturer’s 2-cycle oil. Another alternative is this 2-cycle mix by Kawasaki. It comes in 5.2 oz. and 6.4 oz. bottles that can be mixed with 2 gal. or 2.5 gal. of gas respectively for a 50:1 mix. Use 2 gal. of gas and a 6.4 oz bottle of oil to achieve a 40:1 mix.

2-Cycle Gas to Oil MixChart