How to Mix Gas For Lawn Mower on a Two-Stroke Engine

Do you know how to mix gas for lawn mower? If you don’t, then this article is perfect for you. We will go over the basics of mixing gas and oil in your two-stroke engine.

This information can be applied to any small engine that uses a two-stroke design. You do not need to have extensive knowledge about engines or gasoline/oil mixes to follow along with this article.

All you need is an open mind and a willingness to learn something new.

Read on.

Two-stroke Engine Lubrication

Most two-stroke engines require a gasoline/oil mix to lubricate the moving parts. Two-stroke engines lack oil pumps and rely on the fuel and oil mixture to coat the moving parts.

If you do not mix the correct proportions of fuel and oil, your engine will not run properly, if at all. In this article, we will go over the basics of mixing gas and oil for your two-stroke engine.

do you mix oil and gas for lawn mower

How to Mix Gas for Lawn Mower- Step by Step

Mixing your gas and oil is done in two parts. The first part is how much fuel you will use, and the second part is how much oil to add. Please follow along carefully, so no mistakes are made while mixing gasoline for your engine.

First, you need to know exactly what type of gasoline/oil mix ratio you need. In general, you want to use a 32:1 ratio of gasoline to motor oil.

That means for every gallon of gas you put into your tank. You will add a quarter cup of motor oil. This is a good average mix that most two-stroke engines require.

You can always change this ratio depending on what type of engine. Consult your owner’s manual for more information on what ratio you should be using in your engine.

Also read: Proper disposal of old lawn mower gas

Here is a reference gas/oil mixture ratio chart

Mixing Ratio (Gas: Oil)Volume Of GasolineVolume of 2-Cycle Oil
32:11 Us gal. (128 oz)4 oz.
40:11 Us gal. (128 oz)3.2 oz.
50:11 Us gal. (128 oz)2.6 oz.
32:11 Liter31.25 ml
40:11 Liter25 ml
50:11 liter20 ml

If you are mixing oil into your gasoline, it is recommended that you use a 30 or 40-weight motor oil. These weights refer to how thick the oil is when at room temperature.

You do not want to use lightweight oil because it will not be thick enough during the winter months, and it will burn up quickly in the engine.

You also do not want to use heavy-weight oil because it can cause your gas to burn too slowly. In some cases, using a 50-weight oil can cause you to add too much oil to your gasoline mixture.

Also read: What is the best oil extractor for mowers?

Now that we have established how much gas and oil you need to mix, let’s go over putting the correct ratio into your engine.

Step 1: Open up the gas cap on your lawn mower or other small engines. Make sure that it is set to the “On” position. This will release excess pressure in your fuel tank and prevent accidental combustion.

Step 2: Start up your lawn mower or small engine and let it warm up for a few minutes. This will allow the oil to mix with the gas, rather than just coating the top of it. After letting it run for a few minutes, shut off the engine and wait five minutes for it to cool down completely.

Step 3: It is time to add your gasoline/oil mix into the tank. You want to take your garden hose and fill up the tank until it reaches the very top edge of the gas cap opening. This will be around one gallon of mixture for most smaller engines.

Make sure that you do not pour too much gas into the tank, as this will cause excess spillage and may even damage your engine. Also, try to avoid spills as best as possible so you do not make a mess that needs to be cleaned up later.

Step 4: After filling the tank with gasoline and oil mixture, it is time to start up your engine and let it run for a few minutes. Keep the engine running for about five to ten minutes, allowing everything to mix together inside of your lawn mower or small engine properly.

This is a crucial step to get the ratio correct and increase the life of your engine.

If you do not feel comfortable performing these steps, it may be a good idea to have your local lawn mower shop mix the fuel mixture for you. This will allow you to rest assured, knowing that they are mixing it to the right specifications for your engine.

Also read: Which oil suits Kawasaki lawn mower engine

FAQ’s- How to Mix Gas for Lawn Mower

What Happens If You Mix Gas and Oil Wrong?

Suppose the gasoline to motor oil ratio in two-stroke engines is incorrect or improperly mixed. In that case, the mixture may ignite the cylinder, producing excess heat that could cause engine damage.

The heat generated by incompletely burning fuel can damage piston rings and other parts, but this problem will not be visible without an engine inspection.

Do I Need to Mix Gas and Oil in My Lawn mower?

If you are using a two-stroke engine in your lawn mower, you will need to mix the gasoline and motor oil.

Using a two-stroke engine means that a crankshaft-powered piston will perform the functions of an air compressor, which causes a vacuum that draws in fuel and oil mixture into the combustion chamber.

Will Oil in Gas Harm Engine?

Oil in gasoline will not harm the engine unless it has been sitting for a long period.

In this case, adding oil to gasoline will dilute the mixture. If this happens, just be sure to mix it in properly when refueling your engine.

Process of killing tree stumps with motor oil.

As you can see, it is not difficult to mix gas and oil on a two-stroke lawn mower. You may want to make sure the engine has been cooled before mixing.

Be sure that your mixture ratio is correct for optimal power and fuel efficiency performance. We hope this information has been useful as we look forward to hearing from you with any questions or comments.

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