For the best performance of your lawn mower engine, you want to make sure you use fresh, clean fuel with a gas stabilizer. Keep in mind that most ethanol-based fuels degrade over time and can lead to such as poor starting and performance of the mower’s engine. So, what type of gas is best for lawnmowers?
Both 2-stoke and 4-stroke lawn mower engines use clean regular unleaded gasoline with a minimum octane rating of 87 with 10% or less ethanol. You can also use premium gas with a higher octane rating, such as 91 and 93. Two-cycle mowers can use regular or premium gas mixed with good two-cycle engine oil.
What kind of gas do lawnmowers use?
The best gas to use in a lawn mower depends on the engine type. Most four-stroke engines use fresh clean unleaded gasoline with an octane rating of 87 or higher. You might opt to use gas that contains not more than 10% ethanol.
Mowers with two-stroke engines use fresh unleaded gasoline with an octane rating of 87 or higher but with an addition of high-quality two-cycle engine oil. Therefore, they can run on either regular or premium gas.
Overall, lawn mowers use octane gasoline that has the following qualities:
- Is fresh and clean;
- Contains a minimum octane rating of 87;
- Has 10% ethanol or less.
As such, both regular and premium unleaded gasoline is recommended for lawnmowers.
What type of gas to avoid for your lawn mower
While you can buy regular gasoline at your local gas station for use in your gas push lawn mower, only fuel with a maximum of 10% ethanol is recommended. Most gas stations sell fuel with up to 85% ethanol, which is not good for small engines such as gas lawn mowers, gas-powered lawn edgers, etc.
See the table below for the type of fuel to use and the type to avoid for small engines:
Is it okay to use premium gas in a lawn mower?
You can certainly use premium high-octane gasoline in your lawn mower. However, it is recommended that you check your mower’s manual before using premium gas.
Most engines are designed to use minimum octane-rated gasoline; therefore, anything higher than that can easily damage the mower’s fuel system. Additionally, in most cases, there are no benefits, yet premium gas costs 5 to 20 cents per gallon more than regular gas. You need a higher compression ratio to get the advantage of higher octane numbers.
That being said, there is no harm in using premium gas in your lawn mower but don’t expect that it will improve your mower’s performance.
Regular vs premium gas for lawn mower
If you are trying to decide what gas is most appropriate for your gas push lawn mower, the first step is to read your owner’s manual to see what gasoline the manufacturers require. It is advisable to stick to the manual because any defects arising from using the wrong gasoline breach warranty.
The next step involves the compression ratio of your lawn mower. For optimal performance, mowers with high compression ratios require high octane fuel found in premium gas. However, most mowers are optimized to run on regular gas.
Premium petrol has a higher octane rate meaning that less filler is added to the gas, thus making it purer. However, lawn mowers can run on lower octane gasoline; therefore, premium gasoline is unnecessary. So why pay more for premium gas when regular gas can serve your mower?
Premium gas has fewer additives, but you still need the same amount of gas to run your mower. This means that you are not using better gas because you will still use the same amount but pay more if you use premium gas.
Premium gas is most suitable for the winter season, while regular gas is most suitable for summer seasons.
There is no harm in using premium gasoline; however, I recommend that you use regular gasoline because it costs less and offers the same performance to your mower as premium gas would.
Recommendations and Considerations
While there are many types of fuel to choose from for lawn mowers and other small engines for yard work, you might want to stick to the manufacturer’s recommendations for the best performance. But that’s not all; other factors may also come into play when selecting the right type of gasoline for your lawn mower.
Here are some important recommendations and considerations:
Use 87-octane, 10% ethanol gas
As a rule of thumb, a minimum of 87-octane containing up to 10% ethanol is the recommended gas for lawn mowers. Ensure that the gas is fresh and clean, as these fuels degrade rather quickly. Using leftover fuel from last season before winter might not be a good idea.
Beware that gas stations today also sell gasoline with 15% to even 85% ethanol. These are not approved for use in small engines such as lawnmowers, edgers, weed eaters, etc. Always check before you pump.
No mixing gas with engine oil
Do not mix gasoline with oil if the manufacturer does not recommend it. Also, avoid modifying 4-stroke small engines to run on alternative fuels because it will damage the fuel combustion system of your lawn mower. Manufacturers do not cover such damages under their warranties.
Check the label or manufacturer’s manual to determine if you have a 2-cycle or 4-cycle gasoline engine to ensure the type of petrol your lawn mower uses.
A minimum of 85 octane gasoline is recommended at high altitudes above 5,000 feet to remain emissions-compliant. You may need high altitude adjustment for your engine if you live in a high-altitude region to maintain the optimum performance of your lawn mower on its recommended type of gas.
Without such an adjustment, you may experience decreased lawn mower performance, increased emissions, and increased fuel consumption.
If you’re in colder climates, you should consider consuming stored gasoline within that season to ensure you maintain the performance of your engine.
Use additives to reduce fuel degradation
Since gasoline at the pump contains ethanol, you want to keep it from degrading over time and also from damaging the components of your lawn mower’s engine.
Use the official fuel additive recommended by your lawn mower manufacturer to prevent corrosion caused by moisture in fuels blended with ethanol.
Verdict: What’s the Best Gas for Lawn Mowers?
The best gas to use in your lawn mower is that recommended by its manufacturer. The rule of thumb is that you can use either regular gas rated at 87 octanes or premium gas that’s rated higher at 91 or 93 octanes. Do not use more than 10% ethanol gas to avoid damage to the mower’s fuel system.
If the manual recommends premium gas, that’s the type of gas that will give you the best performance. If you use regular gas instead, the engine will be damaged after a while. On the other hand, if it requires you to use regular gas, you MUST use it.
In the absence of such a requirement, the best fuel for your lawn is gas:
- That has a minimum of 87 octanes.
- Fresh. Fresh gas prevents varnish and gum formation.
- With up to 10% ethanol or 15% methyl tertiary butyl ether (read the labels on your products to know their content).
- That is canned. Canned gasoline combines ethanol-free unleaded gas with a fuel stabilizer to prolong its life. Canned fuel products such as Briggs & Stratton advanced formula ethanol-free fuel are suitable.
- Low octane rating for the summer season.
- High octane rating during winter.
The best gas to use for your lawnmower is the one that is required in your owner’s manual to avoid damage and breach of warranty. However, if your manual does not require any gas, you can use any octane gas with a minimum rate of 87 and available at a refilling station.
Does high-octane gasoline enhance performance?
Higher octane in premium gas will not enhance your mower’s performance, but it is not harmful. You should use it during winter but ensure you have cleaned out your engine before you change gasoline.
Regular gas is cheaper and ensures performance; it is best for summer. You may choose either but consider their prices.
Your biggest concern should be the amount of ethanol that is present in the gasoline. Lawn mowers need a maximum of 10% ethanol in their gas, so anything above that will corrode your engine.
It is better to buy canned gas like Briggs & Stratton’s advanced formula ethanol-free fuel because you can analyze its ingredients and see its ethanol content. It also comes properly mixed and ready to use.
Pro tip: Do not mix oil in gasoline or modify your mower’s engine to run on alternate fuels. It might cause damage and void your manufacturer’s warranty. Avoid using leftover fuel that has been kept for more than 30 days.
- Peter Dunn, MIT: Difference Between Premium-Grade and Regular Gasoline
- US Environmental Protection Agency: National Emissions from Lawn and Garden Equipment