You pull up to the gas pump to buy fuel for your Exmark mower and realize there are many options available. What type of fuel does your Exmark use and which fuel grade should you buy? 

Most Exmark lawn mowers will have four-stroke engines that use unleaded gasoline. Fresh gas to be consumed within 30 days with an octane level of 87 or higher and an ethanol percentage no greater than 10% can be used in your Exmark. Read on for exceptions.  

While most Exmark mowers use unleaded gas, it is important to read your manufacturer’s operator’s manual to determine what type of fuel is recommended for your lawn mower. 

Exmark also carries diesel and propane lawn mowers in their product lineup, so it is crucial you consult your manual if you are unsure whether your engine uses unleaded fuel or not. 

type of gas to use in an Exmark lawn mower

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Follow all safety instructions provided in your equipment operator’s manual prior to diagnosing, repairing, or operating.Consult a professional if you don’t have the skills, or knowledge or are not in the condition to perform the repair safely.

Keep These Tips in Mind When Buying Fuel for your Exmark: 

  • Make sure your gasoline octane is 87 or higher
  • Do not use fuel with ethanol percentages greater than 10%
  • Do not let your fuel collect moisture by storing it outside
  • Buy enough fuel that will be consumed within 30 days

Tips When Choosing Gas for Your Exmark Lawn Mower 

It is best to run a good fuel through your Exmark for its longevity and run ability. Follow these tips to keep your lawn mower running without clogging up the fuel system. 

Always Buy Fresh Gas for Your Exmark 

Gas breaks down over a short period of time. It is best to use fuel within 30 days. As tempting as it may be to show up at the gas station with a large fuel container, so you make fewer trips, it is not good to run store gas for long periods of time. 

Because it is best to use your fuel within 30 days, you want to buy fuel from a busy gas station. You don’t want to go to a gas station where you rarely see vehicles at the fuel pumps. This may mean having to drive past the little roadside gas station to a gas station near a busier town. 

Avoid Using Fuel with High Ethanol Percentages in Your Exmark 

While ethanol can be an advancement in the fuel world and very beneficial overall, it is not always best for small engines. When it comes to Exmark mowers, the lower the ethanol percentage, the better.

If you are unfamiliar with ethanol, it is essentially a corn-based fuel that is more environmentally sound. When you visit your local gas station, you will often see that there is a percentage of ethanol mixed with gasoline.

Various gas stations will offer different percentages of ethanol, but on average, it will be between 10 and 15 percent. Ideally, you will want to avoid using gasoline that has above a 10% ethanol content in your Exmark mower.  

Some things to keep in mind about ethanol and how it can affect your mower are:  

  • Always avoid gas that is marketed as E85! This gas is used in some areas and is 85% ethanol. This will cause damage to small engines like those used in mowers.   
  • While ethanol works well in most motor vehicles, it is damaging to use in small gas engines. Ethanol-based gas attracts moisture from the air. This will cause the gasoline to separate from the ethanol. Gas sinks to the bottom of the fuel tank.
  • The ethanol that separates from the gas in the tank will be fed through the engine causing ignition problems for your Exmark mower.
  • Another major issue that can arise from ethanol is due to the corrosive nature of the product. High ethanol levels can burn very hot, which can cause overheating in small engines. Overall, this can cause irreversible damage to the engine.

If you absolutely cannot find gas that is ethanol-free or below 10% ethanol, you will want to add an extra fuel treatment. These treatments are easy to find and can help stop fuel from separating.   

Buy High-Quality Fuel for Your Exmark 

If you are able to buy a higher quality gas for your Exmark mower, I highly recommend it. A higher quality fuel with less ethanol helps reduce the deposit build-up in your carburetor and other parts of your fuel system. 

I like using recreational fuel or premium unleaded fuel in my Exmark. I add a fuel stabilizer to my premium unleaded gas to extend its life, so I don’t have to worry about wasting it when I don’t use it within 30 days. 

I prefer to use a product called Sea Foam. You can read more about it in my article “Why Use Sea Foam Fuel Additive in a Lawn Mower”. 

How to Store Unused Gas for Later Use in Your Exmark

Use a Plastic Gas Can

The plastic gas can you choose must be designed to store unleaded gas. Some plastics are not designed to store gas and will break down. 

Add a Fuel Stabilizer

Add a fuel additive to the can with the gas that will not be used right away. This will help keep any gas that you may have leftover as fresh as possible.  

I like Sea Foam fuel stabilizer because it stabilizes fuel for up to two years and reduces moisture buildup. Moisture is not good for the fuel system. 

Avoid Storing Over a 30-Day Gas Supply

Try to avoid buying more than a 30-day supply of gas. The quicker you use the gas, the better. However, it can be hard to know exactly how much you have in your tank and how much you will need with each mowing.  

Rotate Gas

Cycle your gas. Always use the oldest gas supply before using the new gas. This will ensure gas does not sit for months at a time. 

Discard Fuel at the End of the Mowing Season

At the end of the season, discard any gas you have left. You can recycle it or simply use it in your unleaded gas vehicle. Read our article on winterizing your lawn mower to learn about steps to take care of your Exmark at the end of the mowing season. 


Once you get the hang of buying gas for your Exmark mower, it is relatively simple to know what you need and when you need additional gas. By adding a fuel stabilizer and routinely alternating through your gas, you will not waste expensive gasoline, and it will be well worth the price.  

Here are the basic items to keep in mind when you are purchasing fuel for your Exmark lawn mower. 

  • Buy fresh fuel from a busy gas station
  • Use a fuel stabilizer as needed
  • Avoid high ethanol percentages (>10%)
  • Buy unleaded gas with an octane level of 87 or greater
  • Refer to your Exmark owner’s manual for additional help

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