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Can You Put Car Gas in a Lawn Mower?

Can You Put Car Gas in a Lawn Mower?

Summertime is here and the grass is starting to get long. You go to start the lawnmower and quickly realize it is out of gas. If you’re in a pinch, you may wonder if you can use car gas instead of mower gas.

For most lawn mower engines, you can use regular or premium unleaded gas, much like you would use in your car. The gas you put into your lawnmower should have an ethanol rating anywhere of 87 or 91. Gas for a lawnmower should contain about 10% ethanol to protect your engine.

There are so many questions surrounding gasoline and what can or cannot be used in a lawnmower or any other small engine. We have put together some information to help you determine what type of gas would be best for your lawnmower.

How Can I Know if It Is Safe?

If you filled your tank up at the gas station, it is pretty easy to tell exactly what is in your gasoline as it usually tells you on the pump what the ethanol rating is for regular or premium unleaded gas.

A good rule of thumb is that if you don’t know what is in your gas tank, then it is probably not smart to pour it into your lawnmower.

After a period of about 30 days, gasoline can oxidize and can harm your lawnmower if it is used. Sometimes, it is hard to tell if this is the case with your gasoline, but there are a couple of things that you can do to determine if your gasoline is still good to use.

The first thing you can do is check the smell.

Now, be careful! We are not encouraging anyone to directly breathe in the gasoline to determine if it is still good, but it is ok to just take a little sniff. If your gasoline has kind of a sour smell, then that is probably a sign that it has gone bad.

Another way that you can check your gasoline is by pouring some of it into a clear container. If your gas has a darker color (like brown or black) then it has probably gone bad.

If your gas has been sitting in your garage throughout the winter, it is probably pretty safe to assume that it has gone bad, but if you feel the need to check, the methods we mentioned above will help you determine if the gas is safe to use in your lawnmower. Remember, it is always best to be cautious when you’re dealing with gasoline, engines, and lawnmowers.

Gas is expensive, and we don’t want to spend more than we have to but, a couple of gallons of gas is going to be much cheaper to replace than a brand new lawnmower.

2-Stroke Engines

It is extremely important that you know exactly what kind of gas the manufacturer recommends you use in your lawnmower. Although we have mentioned above that regular gasoline is acceptable to use in lawnmower engines, that generally only applies to your most common 4-stroke lawnmower engines.

Although your lawnmower is most likely a 4-stroke engine, it is possible that you have a lawnmower that runs on a 2-stroke engine.

If you have a lawnmower with a 2-stroke engine, then you will have to do things a little differently. You can still use the same type of gas that you would use in a car for your 2-stroke engine, but it is also required that you mix some oil into your gas.

You can make this mixture of oil and gas yourself or buy it pre-mixed. The pre-mixed variety tends to come with a high markup, but it’s certainly convenient!

The most common gas to oil ratio for a 2-stroke engine is going to be 50:1. You are not going to be using normal motor oil that you would put in your car, but you will want to buy oil specifically made for 2-stroke engines.

There are also some lawnmowers out there that have engines that require “ethanol-free” gas. You will probably not find any ethanol-free gas at your local gas station. You may have to search around a little bit for it, but there are plenty of companies that make ethanol-free gasoline for just this situation.

The best thing to do if you are still unsure about which gas to use is to check the owner’s manual of your lawnmower. Generally, the owner’s manual will have suggestions on which type of gas is best for your engine.

If you are like the rest of us and you threw away the owner’s manual the same day you bought the lawnmower, then a simple internet search should provide you with the information that you need to fuel your lawnmower.

Premium or Regular?

Another common question asked when trying to determine the best type of gas for your lawnmower is if you should use regular or premium unleaded gas. When you first buy a car, it’s sometimes recommended to use premium gas for the best performance.

In a lawnmower or any other small engine for that matter, it is not as important to use premium fuel. Using premium fuel will not hurt your lawnmower engine at all, in fact, it will work just as well as regular unleaded gasoline.

Premium fuel was made for big engines that are high performance. There are some lawnmowers that are more powerful (especially riding models) but generally, your lawnmower’s engine is not going to be considered high performance.

There are some very slight advantages to buying premium gasoline, but in a small engine, it is not going to be able to accomplish as much as it would in a much larger engine (like your car).

Although premium fuel is not going to hurt your lawnmower, it probably will do a little bit more damage to your wallet compared to regular unleaded fuel!

Ultimately, it is up to you to decide whether premium or regular is better for you, but just know that either way you decide to go, your lawnmower will run just fine.

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Zach Reed

Hi, I'm the founder of! Having owned a wide variety of vehicles in my life, I was astounded at how hard it can be to find answers to common automotive questions. Rather than sit idly, I decided to create this website to help others!