It doesn’t matter if your lawnmower is decades old or whether you’ve just bought it from a hardware store, all lawn mowers will need fuel to power them.
An issue with a lot of smaller lawnmowers is that their engine needs a particular type of fuel.
Petrol stations have various pumps to choose from, so it can be hard to know which kind of fuel you should use.
Different types of fuel, labels, and various prices can make it difficult to understand what type of fuel you’re purchasing.
If you can relate, you’re in the right place!
We’ll cover more about fuel varieties and the best kind of petrol to use in a lawn mower below.
The Best Type Of Petrol To Use In A Lawn Mower
In most cases, the engines in lawnmowers need unleaded gasoline with an ethanol content under 10% and a minimum octane rating of 87.
The majority of premium, mid-range, and regular unleaded petrol fuels fulfil these standards.
This is the case for 4-stroke and 2-stroke engines, but 4-stroke engines only burn gasoline. 2-stroke engines need a mixture of two-cycle engine oil and unleaded petrol.
To give you a short answer, here are some popular fuel varieties and if they are or are not suitable for lawnmowers.
- Diesel: Does not work in a lawn mower
- E15 to E85: Not advised for use in a lawn mower
- Non-Oxygenated Gas: Does work in a lawn mower
- Unleaded 91 ‘Premium’: Does work in a lawn mower
- Unleaded 89 ‘Plus’: Does work in a lawn mower
- Unleaded 87 ‘Regular’: Does work in a lawn mower
Can Lawn Mowers Run On Regular Petrol?
Lawnmowers can use a variety of different fuel options.
For the most part, they can run on regular petrol, though some types of regular petrol have different octane ratings.
Regular petrol generally has an octane rating of 87, which is suitable for all types of lawnmowers.
We’ll go into more detail about the types of fuel suitable for lawn mower engines below:
Unleaded Regular Petrol
This is the most popular and commonly used type of fuel. Regular unleaded petrol tends to have an 87-octane rating and is available at all petrol stations.
This type of fuel has the lowest octane rating that you can purchase, generally being the least expensive choice.
It’s also the lowest octane petrol that you should ever use in a small engine or lawn mower.
Octane defines how much compression gasoline can deal with before combustion.
Fuels with a lower rating can deal with less compression, while ones with a higher octane rating can deal with more.
Octane is important as air and fuel are compressed repeatedly to power petrol engines.
Unleaded Mid Range Petrol
Petrol with octane ratings from 88 to 90 are usually sold as ‘plus’ or ‘mid-range’ types of fuel.
These have a slightly greater octane rating, which means they can manage more compression, making them a little higher in price.
If your petrol station offers regular petrol with an octane rating under 87, it’s better to go with the mid-range option, or premium fuel, which we’ll cover next.
Unleaded Premium Petrol
Premium, or high octane unleaded petrol tends to have a 91 octane rating.
A few petrol manufacturers may offer fuel with a 92-93 octane rating as their most expensive option, but this isn’t very common.
Some car companies advise using premium unleaded petrol, because of its higher octane rating, but people differ over whether it’s worth paying more to use the fuel in lawnmowers.
You can use higher octane unleaded petrol in your lawn mower if you prefer, but it’s not a necessary requirement.
It’s important to know what oxygenated gasoline is before we can get into non-oxygenated gasoline.
The majority of gasoline is oxygenated. Fuel additives, known as oxygenates, are added to increase octane ratings and fuel combustion.
This process helps to lower exhaust emissions.
Ethanol is the most popular type of fuel additive that contains oxygenates.
This is why ethanol is present in practically every type of oxygenated gasoline.
Non-oxygenated gasoline is simply gasoline without ethanol present in it.
Some people do prefer to use fuel that doesn’t contain ethanol or oxygenates.
Increasing the oxygen content in gasoline can increase the chance of moisture contaminating the fuel.
Some prefer to use non-oxygenated fuel in their engines so the moisture doesn’t harm their fuel system.
Non-oxygenated gasoline is usually priced higher than other types and isn’t as readily available to purchase.
The Best Type Of Petrol To Use In Your Lawn Mower
Now that we’ve covered the types of petrol that are suitable for your mower, we can get into the types that are best for its engine.
We’d recommend either using non-oxygenated gasoline or unleaded regular petrol.
They are both very different from each other, so here’s an explanation of when you should use each type.
Unleaded Regular Petrol
Unleaded regular gasoline is a good choice for the majority of lawnmowers.
It has a lower octane rating, but it tends to perform efficiently, even when compared to premium and mid-range petrol options.
This type of fuel will save you money, as while higher-priced fuels may have a greater compression rating, this isn’t a huge benefit when it comes to smaller engines in lawnmowers.
It can be hard to get your hands on non-oxygenated gasoline.
While it isn’t easy to find, non-oxygenated gasoline works very well in all lawnmowers.
It’s also a good choice for more expensive lawnmowers, like riding mowers.
This type of fuel will prevent moisture from contaminating these pricey fuel systems.
Without any ethanol present in it, non-oxygenated gas may even increase the lifespan of your mower’s engine.
Fuels You Should Avoid Using In A Lawn Mower
A lot of different fuel varieties are suitable for use in a mower, but others aren’t compatible with their engines.
Here are two types of fuel that should never be used in a lawn mower.
Gasoline With A High Ethanol Content
Many people are unaware of this point, but around 10% of ethanol is present in the majority of gasoline around the world.
This rings true for unleaded premium, mid-range, and regular gasoline.
Fuels that contain over 10% ethanol are classed differently, like E85 with 85% ethanol, or E15 with 15% ethanol.
These fuel varieties have their purposes, but it is not recommended to use them in your mower.
Fuels that contain more ethanol can lead to corrosion in your engines.
Similar to how petrol should never be used in a diesel engine, diesel should never be used in a gasoline engine.
Diesel is dense and thicker than gasoline, so it will struggle to move through the engine, clogging up your fuel filters.
Remember to double-check what type of fuel you’re using when you’re at the petrol station.
How 4 Stroke and 2 Stroke Mowers Influence Your Fuel Choice
There is only one main difference between the fuel used in 4-stroke and 2-stroke engines.
As mentioned above, 4-stroke engines only burn gas, keeping their engine oil in a different component.
2 stroke engines burn a mixture of fuel and oil.
If your mower is a 2-stroke device, you’ll need to mix the correct amounts of 2-stroke, high-quality engine oil every time you fill the tank.
It’s imperative to use the correct gas-to-oil ratio.
Using too much oil can lead to carbon accumulating, leading to excess smoke and difficulty starting the engine.
Adding too little oil means that there isn’t enough to protect the engine or lubricate the moving engine components.
This can make the engine overheat from the added friction, which can permanently damage the engine as a result.
Other than this difference, both 4-stroke and 2-stroke mowers will use the same type of fuel.
Is E10 Petrol Suitable For Lawn Mowers?
Lawnmowers can run using E10 petrol, but it isn’t recommended. It’s best to use fuel that contains as little ethanol as you can find.
Ethanol attracts water, leading to corrosion and damage to the engine as time goes on.
This is especially true when it comes to older mowers.
The older your lawn mower is, the worse it will handle E10 petrol, particularly for engines that were made pre-2010.
Ways To Make Your Lawn Mower Run Smoother
Other than using unleaded fresh petrol with a good octane rating and a low ethanol content, here are some tips that can make your mower’s engine run more smoothly.
- Check the fuel filter. This may be clogged with debris if your mower is over two years old. Wipe any mess off and use a cleaning product to clean the filter. You can also replace the filter entirely if you wish.
- Change your spark plug (Also check out Simple Steps To Gap A Lawn Mower Spark Plug). This may be worn out or dirty.
- Run fresh fuel with an additive added through the engine’s system. This can help the motor run better if you have used low-quality fuel or older petrol in the past.
The Bottom Line
Now you know which types of fuel are suitable for your lawn mower!
While you can use unleaded mid-range and premium petrol in your mower, it’s best to use unleaded standard petrol, as this will save you more money and won’t affect your mower’s performance.
Remember to avoid gasoline with a high ethanol content and diesel in your mower, as these can make your engine run less smoothly overall.
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