Best Type of Gas to Use in Your Lawn Mower | SOLVED

When you get fuel for the first time for your lawn mower, there are many choices. However, finding the right fuel for your mower doesn’t have to be overwhelming. 

This guide will help demystify the different types of fuel available, so you can determine which types work best for your lawn mower and which ones you should never use in your engine. I’ll also reveal the best type of gas to use in your lawn mower.

Do Lawn Mowers Take Regular Gas?

There are several types of gas for you to use in your lawn mower. However, if you can, why not use the simplest option? Fortunately, most lawnmowers can use regular gas. However, it is essential to note that not all regular gas has the same octane.

What Fuel Should I Use in My Lawn Mower?

You should always check your user’s manual to determine if the mower needs a specific type of gas. If it doesn’t specify a type, unleaded gasoline with an octane rating of at least 87 will do just fine for most lawnmowers. It’s also essential that the ethanol content doesn’t exceed 10%. 

You’ll be able to find gas with these characteristics at most gas stations. However, when I had a mower that couldn’t handle any ethanol, I had to drive out of my way to get gas for it. So, depending on your mower’s specific gas requirements, you may end up having to be a little pickier than normal.

What Is Octane Rating?

Understanding octane ratings can assist you in making a better decision when choosing which fuel to buy for your mower. 

Octane is a rating system that measures how much compression gas can handle before it combusts. Fuel with low octane ratings cannot handle much compression. Conversely, high-octane fuels can handle higher compression levels. 

Octane rating is essential to know because fuel and air are compressed when your lawn mower’s engine is powered. Thus, for a smoother mowing experience with more power, you will want to choose a higher-octane fuel that can handle higher compression levels. 

The lowest you should go is an 87-octane rating. Luckily, most gas stations don’t sell gasoline with lower octane ratings. And, for the most part, most mowers work just fine with gas with an 87-90 octane rating.

However, you should always check your user manual to ensure that your engine doesn’t need a higher octane level. Of course, higher-octane gas costs more. But if your engine requires a higher octane, you shouldn’t use the cheapest gas. 

According to the EPA, engines don’t run as well if you use a lower octane gas than it requires. They say that using the wrong octane will eventually damage your engine and your emissions control system. Using the wrong type of fuel in your tank will also void your warranty so that you can’t get your money back when you eventually end up destroying your engine.

2-Cycle or 4-Cycle Engine and Fuel Selection

Lawnmowers will either have a two-cycle or four-cycle engine. You do not need to know the ins and outs of what that means mechanically. However, you need to know how it affects what type of gas you should use.

Two-cycle engines use a fuel and oil mix, whereas four-cycle engines don’t need you to add oil to the gas because they keep oil in a separate reservoir.

Fortunately, whether or not you need to add oil to your gas is the only distinction between the two engine types. So, you can use the same type of gas in your two-cycle and four-cycle engine lawnmowers. You just need to know whether to add the oil to the gas or place in it a separate reservoir.

What Kind of Gas Does a Lawn Mower Take?

If you have a lawn mower with a two-cycle engine, you will need to mix oil with your gas. However, because two-stroke engines have difficulty meeting emissions regulations, most of today’s lawnmowers have four-cycle engines. Thus, you most likely won’t need to worry about mixing oil and gas.

If you do have a two-stroke engine, we suggest adding the correct amount of oil to the tank before you add the gas to ensure that you have room for the required amount of oil. 

The type of gas you use will affect how your lawn mower functions and how long it can go without a refill. 

Regular Unleaded Gas – Best Gas to Use

When it comes to most lawnmowers, especially those with four-cycle engines, regular unleaded gasoline is the best option for you. Indeed, it is not perfect. It has a lower octane (usually around 87), which has some negative impacts. However, in my experience, regular unleaded gasoline performs as well as mid-range and premium fuels. 

In my mind, it’s not usually worth it to spend extra money on premium fuel when the cheap options work. The main exceptions are if your mower requires a higher octane fuel or you are using the mower in conditions that might strain the engine more. 

Premium fuels have higher compression ratings, but I do not think the extra performance is worth the premium price tag for everyday use. It certainly feels unnecessary considering most of us are using low-end push lawnmowers. Even if you are using a riding lawn mower, it is not necessary to use high-end fuel unless your mower requires it.

Mid-Range Unleaded Gas

Mid-range unleaded gas is, as you would expect, a middle ground between regular unleaded gas and premium unleaded gas. Typically, it has an octane rating of 88 to 90. You also might see mid-range unleaded gas listed as “plus” fuel. 

Since mid-range unleaded gas has a higher octane rating than regular options, it can handle more compression. However, this also means it comes with a bigger price tag. Fortunately, it’s not usually not too pricy. As a result, it can be a reasonable option depending on your financial situation.

Premium Unleaded Gas

Premium unleaded gasoline is another choice, and it is a requirement for some engines. 

Most premium unleaded gas has an octane rating of 91. However, some companies offer options with ratings as high as 92 and 93. Ratings that high are uncommon, but they pop up from time to time.

There are several bonuses to using higher-octane fuel:

  • It often improves gas mileage so that you don’t have to fill your tank as often
  • It reduces carbon dioxide emissions, especially when your mower is working harder or it’s hotter outside
  • It often improves performance

So, you might decide to try a higher-octane fuel if you’re not getting good gas mileage, if you need to mow higher grass or up hills, or if it’s extremely hot outside.

To determine if the better gas mileage is worth it, fill your tank with regular unleaded gasoline and count how many minutes it takes to run out of gas. When you refuel, use premium unleaded gasoline and determine how long it lasts. Then, you can divide the amount of money you spent on each type of gas by the number of total minutes you mowed with each type to determine how many cents per minute each type of fuel costs to use.

Non-Oxygenated Gas

Finally, you can use non-oxygenated gas in your lawn mower. 

Oxygen is added to gas to increase octane rating and fuel combustion, and also to reduce emissions. Oxygenated gas usually contains ethanol as a oxygenate.

So, why would anyone be interested in a fuel that does not contain oxygenates? Adding oxygen to gas can contaminate it with extra moisture. According to Angi, oxygenated fuel that stays in a lawn mower for three to six months often results in clogged gas lines and filters. As a result, many people seek out non-oxygenated gas for mowers they do not use frequently. However, it’s still likely to go bad if you leave it in the tank for six months.

Fuels to Avoid Using in Your Lawn Mower

Most gas is safe to use in your lawn mower, but there are some types you should never purchase.

High Ethanol Gas

Almost all types of fuel in the United States contain ethanol. Fuel without ethanol is always best, but up to 10% ethanol is acceptable for many engines. However, when you pass that marker, you run the chance of ruining your engine. 

Fuel with 10% ethanol keeps a small amount of water in the solution. However, when the ethanol amount goes above 10%, the water separates from the gas. And water is always bad news for your engine. 

The following types of fuel have more than 10% ethanol:

  • E15 gas: Contains 15% ethanol 
  • E85 gas: C contains 85% ethanol 

While these fuels have their uses, you should never use them to fuel a lawn mower. 

The high water content in high-ethanol fuel will increase the pace of corrosion in your engine. In large engines, the ethanol content gets diluted, but in smaller engines like those in lawn equipment, it rapidly increases the corrosion process.

Ethanol-Blended Vs. Ethanol-Free Fuels

Because ethanol-blended fuels have increased water content, any level of ethanol has the potential to lead to corrosion. The higher the ethanol content, the faster you can expect your engine to corrode and stop working. Your lawn mower may not be able to handle any ethanol at all. So, it’s essential that you read your user’s manual to know how much it can handle and check the ethanol content on the pump at the gas station before fueling.

Because ethanol-free fuels have a lower water content, they are always the better choice for lawn equipment. With ethanol-free fuels, you don’t have to worry about engine moisture and corrosion as much. 

If your mower can handle ethanol and you can’t find ethanol-free fuel, you’ll want to look for fuel that has between 5% and 10% ethanol. Just be sure to avoid E15 and E85 gas. 

Diesel

Finally, you should avoid using diesel to fuel your lawn mower. Diesel should never go in a mower engine. 

If you put diesel in the gas engine of your lawn mower, you could do irreparable damage to it and will certainly void any warranty. So, you should always double-check to ensure you are using gas and not diesel when you are at the pump.

Maintaining a Healthy Lawn Mower Fuel System

You do not want to buy a new lawn mower every few years. To ensure you do not need to do that, you must maintain your lawn mower’s fuel system.

Using Fuel Stabilizer to Protect Your Mower

If you store lawn mower gas for longer than a month, it will begin breaking down. Gas that has an ethanol blend has an even shorter lifespan. Fortunately, you can use fuel stabilizers like Stabil to project your lawn mower. Fuel stabilizers act as antioxidants, slowing the degrading process of fuel. They do this by absorbing water particles.

Verdict: Type of Gas to Use in Your Lawn Mower

Most mowers take regular gas, but there are superior options. Plus, some mowers have very specific fuel requirements. If you use the wrong type of gas in your lawn mower, you can ruin it and end up needing to purchase a new one sooner than you’d planned. 

Fortunately, there are several fantastic options available. Generally, the best type of gas to use in your lawn mower is high-octane, unleaded, non-oxygenated gas with no ethanol. However, regular unlead gasoline usually works fine, and it’s always best to check your user’s manual before making your gas choice.