If you head down to the gas station to fill up a gas can for your lawn mower, you’ll be faced with a row of different options to choose from. Now you know you don’t want diesel, but which type of gas should you get for your mower? While any gas will technically work, some are better for your mower than others. So, let’s go over the different fuels available and figure out how to choose gas for your lawn mower.
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Best Gas for Lawn Mowers (Overview)
The majority of lawn mower manufacturers and lawn mower engine manufacturers recommend that you use regular unleaded 87 octane gasoline with a 10% ethanol content. This includes lawn mowers that have either 2-stroke or 4-stroke engines. If you use high-octane gasoline in your lawn mower, you will likely encounter performance issues and engine damage.
Types of Gas for Lawn Mowers (What’s Available)
Depending on where you live in the country, you’ll have different pumps and fuel options. For example, all states sell E10 fuel, about 30 states sell E15, and just a few are allowed to sell ethanol-free fuel for watercraft and 2-stroke engines. This means the type of fuel available to someone in Florida isn’t the same as someone in New York.
So, how do you choose gas for a lawn mower? Well, you go by what the manufacturer recommends and avoid what they don’t. So to better understand what the different gasoline types are and what all the numbers and references mean, let’s take a closer look at what is available.
Gasoline Octane Rating
First of all, what does octane mean? Well, octane refers to the pressure at which gasoline will ignite or spontaneously combust. So, the higher the number, the more stable the gasoline is, and the more pressure is required to ignite the fuel. So, an engine that produces high compression, such as an old sports car, is better suited to a higher octane fuel.
A lawn mower engine doesn’t create the same pressure as a car and therefore requires a lower octane fuel such as 87 regular gas. So if you use high-octane fuel in your lawn mower, the fuel won’t reach the right pressure and will struggle to ignite. Also, the high-octane fuel could ignite slowly and potentially at the wrong time. Meaning that as the lawn mower passes the compression stroke and begins the exhaust stroke, fuel still has the opportunity to ignite and push the piston. If fuel ignites too late, it can damage the engine and cause it to struggle.
Ethanol Rating
Ethanol in fuel mainly comes from corn and is added to fuel for two main reasons. First, ethanol is more environmentally friendly, and second, ethanol actually has a pretty high octane rating. However, a higher ethanol content produces less energy. So your lawn mower likely won’t perform as well as it should. Also, ethanol reacts with oxygen, producing an acidic compound that corrodes metal. So, using a higher-rated ethanol fuel such as E15 may cause corrosion in your lawn mower fuel system and engine. This is why lawn mower manufacturers don’t recommend using E15 fuel.
Which Gas to Use for a Lawn Mower (My Recommendation)
Because your lawn mower’s engine is designed to create a specific amount of power, handle certain conditions, and withstand limited forces, picking the right gas is key. Using the gasoline type your lawn mower engine was designed to use is important to achieve maximum performance and a long lifespan. So if you’re wondering, “What fuel should I use in my lawn mower?” I’d stick with what the manual recommends and avoid the other options.
As I said in the beginning, just because most fuels will work in your lawn mower doesn’t mean they are suitable. So, to make things a bit simpler, I’ve created this table to show all the fuel options available and which one I recommend for mowers.
| NAME | OCTANE | ETHANOL | SUITABLE | WILL IT WORK |
|---|---|---|---|---|
| Regular | 87 | 10% (E10) | YES | YES |
| Regular | 88 | 10% (E10) | NO | YES |
| Mid-Grade | 89 | 10% (E10) | NO | YES |
| Premium | 93 | 10% (E10) | NO | YES |
| Regular | 87 | 15% (E15) | NO | YES |
| Regular | 88 | 15% (E15) | NO | YES |
| Mid-Grade | 89 | 15% (E15) | NO | YES |
| Premium | 93 | 15% (E15) | NO | YES |
| Flex Fuel | 100-105 | 85% (E85) | NO | NO |
| Non-Ethanol (REC-90) | 90 | 0% (E0) | NO | YES |
| E-Diesel | 45-50 | 15% (E15) | NO | NO |
