Last Updated on May 10, 2022 by Grow with Bovees
Using fresh, clean fuel that’s been pumped at the gas station within the last 30 days is the best type of gas for your lawnmower to keep it running smoothly and efficiently.
But you may be wondering if you should be using premium or regular?
Does it make a difference?
We’re here to answer all your questions on using either regular or premium gasoline for lawn mower engines and other OPE, so read on to find out more.
Types of Fuel Not Suitable for Your Lawn Mower
Let’s first look at the types of fuel you should definitely avoid for most outdoor power equipment.
Obviously, make sure you use gas in a gas powered push along mower or diesel in a diesel powered one. Do not put diesel in small engined garden equipment that runs on gasoline under any circumstances
Push lawn mowers that run on gasoline are far more common, so that’s what we’re focusing on with this article.
When you buy gasoline for your OPE at the local gas station, make sure you only purchase fresh fuel with a maximum of 10% ethanol (gasohol) or 15% MTBE (methyl tertiary butyl ether).
Some filling stations now sell a 15% blend or even petrol with up to 85% ethanol. Of course you can also use ethanol-free fuel as well.
The mixes higher than 10% are not recommended and may cause damage to your engine if used.
So What Kind of Gas Do Lawnmowers Use?
The best gas to use depends on the engine type in your lawnmower.
If your mower has a two-stroke cycle small engine, then use a 40 to 1 or 50 to 1 gas oil mix of fresh unleaded gasoline that has an octane rating of at least 87 with good quality 2 cycle engine oil. You can use either regular or premium gas with maximum 10% gasohol.
Most 4-stroke (or four cycle) engines run on unleaded gasoline with at least an 87 octane rating and of course not more than 10% ethanol. Again, this means you can use either regular or premium fuel.
Note, this may be different if you are at high-altitude. See below for more details.
So to summarize, gas powered lawn mowers use unleaded fuel with the following qualities:
- Clean and freshly pumped (fuel can deteriorate in as little as 30 days)
- Two stroke engines require a gas/oil mix
- Has a minimum octane rating of 87 / 87 AKI (91 RON)
- Has 10% ethanol or less
- Regular or premium is fine
Use a Fuel Stabilizer to Increase Storage Life and Protect the Engine
As most gasoline at the pump these days contains ethanol (remember only use a maximum of E10 blend) the fuel will degrade over time, in as little as 30 days in fact!
We recommend adding a fuel stabilizer product like Stabil vs Seafoam to your gas can when you fill up, as this will stop fuel degradation for up to 24 months of storage.
Can I Just Use Premium Gas in my Lawn Mower?
In general, there’s no reason you shouldn’t use premium (or plus, super etc.) high octane gasoline in your OPE, but make sure to check in your owner’s manual just to make sure.
Using a higher grade fuel will not harm your engine, but don’t expect to see much in the way of performance boost with premium gas.
It’s certainly not worth the extra 5 to 20 cents per gallon you will probably pay over regular gas so unless your machine needs it, then it’s probably not worth it.
Most mowers are set up to run on regular gas (87 octane) rather than premium grade fuel but check with the manufacturer to make sure as some engines may have a higher compression ratio that requires the higher octane ratings found in premium gas for optimal performance.
Summer or Winter Gas?
It would be best to also check the manual for advice on the recommended RVP rating for the quality fuel used in your mower engine.
Gasoline refineries lower or raise the fuel RVP rating throughout the year to get the optimum performance out of their gas according to the air temperature:
- Summer Fuel = low RVP rating
- Winter Fuel = high RVP rating
Note: this rating and when it changes will vary from state to state.
Using a Mower at High-Altitude
At high altitudes of above 5,000 feet (1524 meters), it’s acceptable to use gas with a minimum 85 octane / 85 AKI (89 RON).
You will also need to make the high altitude adjustment to the engine to remain emissions compliant.
Operating the mower without this adjustment will cause increased fuel consumption, increased emission and decreased performance so make sure to check the manufacturer’s instructions on what to do.
Mixing Engine Oil in Gasoline or Alternate Fuels
Unless using a mower with a 2-cycle or two-stroke engine, do not mix your gasoline with engine oil if it’s not recommended by the manufacturer such as those from Briggs & Stratton.
Always check the label on the engine or refer to your owner’s handbook to determine the type of engine your lawnmower has (2-cycle or 4-cycle) and what type or mix of fresh fuel type it needs.
Also, it’s not a good idea to modify small 4-cycle engines to run on any types of alternative fuels as it will damage the engine beyond repair. The Manufacturer’s warranty will not cover this type of damage.
Verdict: Regular or Premium Gas for Lawn Mower Engines?
As we’ve mentioned a few times, the best type of fuel to use for OPEs with small engines like your lawn mower is the type of gas that the manufacturer recommends.
However, if you can’t find that out easily, then the rule to go by is to use either regular 87 octane gas or higher octane premium gasoline that’s rated at 91 or 93 AKI. Remember, when buying it from a garage selling gasoline, make sure to check the labels and do not buy anything with more than 10% ethanol to avoid damaging the lawn mower engine.
If you live at high-altitude you can use 85 octane regular unleaded fuel instead, but you must adjust the engine to its high-altitude setting.
Also make sure you are following the recommended RVP ratings for your machine and location.
If the manual actually recommends using premium gas then that’s the one to go for as it will give you optimum performance and fuel economy. Using regular gasoline could damage small engines that require premium as well as causing it to run poorly.
However, if it doesn’t need the higher octane gas as regular fuel, then using it is a waste of money as it will not increase performance or give you any benefit in the way of increased performance.
As we know, it’s important to add a fuel stabilizer, especially with today’s ethanol blended fuels so make sure you add fuel treatment to the fresh gasoline you’re using for your lawn mower.
So to recap on the correct type of gas to use in your lawn mower the one recommended in the manual.
Or if you can’t find that out:
Fresh fuel with a minimum 87 octane rating.
Ethanol free or up to 10% ethanol (sometimes labeled as E10) or 15% MTBE (methyl tertiary butyl ether) mix.
Do not use E15 (15% ethanol) or E85 (85% ethanol) under any circumstances.
You can also use canned fuel such as that from Briggs & Stratton which is ethanol-free and already contains fuel stabilizers that prolongs it’s life.
Do not use any alternate fuels in your lawn mower’s engine.
Using either regular or premium gas in your lawn mower is going to be fine unless the manufacturer recommends using one or the other.
It will not adversely affect your engine or fuel system in any way to use premium gas but we suggest if you have the choice, using just regular with an 87 octane rating and a maximum of 10% ethanol is the best fuel to use for most lawn mowers.