Do You Mix Oil and Gas for Lawnmower? (What You Need to Know)

If you’re a new lawnmower owner, you might be wondering, “Do you mix oil and gas for a lawnmower?” And if so, what’s the oil and gas ratio you should add? 

The short answer is that 2-cycle engine lawnmowers require a gas and oil mixture for fuel, while 4-cycle engines run on straight gasoline. The most common gas and oil mix ratio for lawnmowers are 50:1, but you’ll want to refer to your owner’s manual for your particular model’s recommended gas and oil mixture ratio.

This can be confusing, primarily if you’ve never owned a lawnmower. 

In the following paragraphs, we’ve provided all the information you need to help you answer any questions you may have regarding this topic, so stick around.

Do You Mix Oil and Gas for Lawn Mower?

You might be able to mix oil and gas and add them to a lawnmower. However, it’ll all depend on the type of engine your mower has. 

Some engines allow you to add oil and gas together, while others will only work if you add them separately. This is why it’s essential to know the type of engine your unit is housing before you start mixing oil and gas. 

What Engines Can You Mix Gas and Oil In?

Lawnmowers typically house one of two types of engines. The first is the two-cycle/cylinder engine, and the second is a four-cycle/cylinder engine. 

If you own a two-cycle engine, you can add a mix of gas and oil. But, per contra, if you own a four-cycle engine, you need to refrain from mixing the gas and oil, or it may damage your engine.

If you checked and saw that you own a four-cycle engine, you’ll also notice that there are different tanks and openings where you can add oil and gas separately. 

How to Know If You Own a Two-Cycle or Four-Cycle Engine?

There are many ways you could differentiate between a two-cycle engine and a four-cycle one. The most common way is to check the engine’s port. If it only has a single opening, then it’s a two-cycle engine, and you can add your oil and gas mix without any worries. 

If you find two ports separating two tanks, then it’s a four-cycle engine, and you’ll need to add your gas and oil separately. 

Another way to recognize the engine’s type is by checking if there are any warning stickers against mixing oils and fuel. You might also find them already labeling the engine as either two-cycle or four-cycle—they can also be called two-stroke or four-stroke, respectively. 

If you have any trouble finding out the type directly from the engine, you can check the user’s manual that came with the mower. The manufacturer will always mention whether it’s a two or four-cycle engine in the manual. 

What Is the Correct Oil-Gas Ratio to Add to Your Lawn Mower?

If you checked your engine type and found it to be a two-cycle, you can now add in your gas and oil mix. But before you do, you need to make sure you’re adding the appropriate amount. 

The amount of gas and oil mixture you add will depend on how much your engine requires. Some two-cycle engines use a 50:1 gas to oil ratio; others use 40:1. Some older models may use 32:1.

You can check the ratio your engine uses by checking the port. Most engines will have the ratio written on the cover. If it’s not there, you’ll find it written in the user’s manual.

If you found that your engine uses a 50:1 ratio, you’ll need to mix around 2.6 ounces of oil with 1 gallon of gas. 

If your engine uses a 40:1 ratio, add 3.2 ounces of oil to 1 gallon of gas. The 32:1 ratio will need 4 ounces of oil added to 1 gallon of gas. 

What Type of Oil and Gas Should You Use? 

Most manufacturers will include what type of oil and gas you should use on your grass cutter in their manuals. So checking the manual is a must. 

If you have any trouble with the user’s manual, you can refer to the recommended type for each engine. 

It’s advised for both two-cycle and four-cycle engines to use an unleaded gas with a minimum 87 octane rating and a maximum of 10% ethanol

Most gas stations sell fuel with more than 15% ethanol, so be sure to check the ethanol percentage when buying your gas. It shouldn’t exceed 10%, or it may damage your engine.

As for the oil, there are oils available specifically for two and four-cycle engines, respectively, so it’s best to use them for your lawnmower depending on the type of engine you have. 

How to Mix Your Gas and Oil Before Use?

Now that you have the gas and oil you need, you can start preparing your mix to use on your mower. Refer to the previous section to know the correct gas to oil ratio you should use.

The first thing you’ll need to do now is to prepare an empty gas bottle. Then, make sure it’s completely clean before adding the new gas. 

Afterward, you can add in your oil and then start mixing. You can mix it up by stirring or shaking the bottle well. That should get your mixture ready for use. 

Please note that you’ll need to use this gas-oil mixture for one month, or it’ll start losing its effect. 

What Happens If You Add the Oil and Gas Mix to a Four-Cycle Engine?

All the previously mentioned steps are specifically for two-cycle engine use. Now, what if you accidentally added this newly made mix into a four-cycle engine instead? 

As long as you notice the mistake quickly, there shouldn’t be much of a problem. You’ll need to drain all the mixture you just added out and replace it with the correct gas or oil per tank. 

If you turn on your mower before you drain the mixture, it may, unfortunately, be too late, and you’ll start noticing your lawnmower smoking up. 

Using an oil and gas mix on a four-cycle engine will cause it to overheat and eventually break down. So it’s best to be entirely sure of which type of engine your lawnmower has before use to avoid causing any damage. 

How Often Should You Change Your Gas and Oil?

It’s recommended to replace your gas and oil mix after three weeks to one month of use. You can wait until two months to replace it, but it won’t be as effective anymore. 

That’s why it’s better to use a new mixture every three weeks to get the best results and make sure you don’t exhaust your engine.


Lawnmowers tend to have two types of engines, and depending on which type they have, they can use a gas and oil mix, or you’ll need to separate the oil and gas from each other. 

If you have a two-stroke engine, you can mix gas and oil without any problems. However, if your mower is equipped with a four-stroke engine, you can’t mix gas and oil. That’s why you need to know the difference before using it.

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