Refuelling a lawnmower: more complex than you think
Optimal lawnmower operation begins with refuelling. Find out all you need to know here.
21.11.2025
Overview: Refuelling a lawnmower
A petrol lawnmower can be refuelled using any conventional premium fuel from a petrol station.
2-stroke lawnmowers need to be refuelled with a mixture of (premium) petrol and oil.
There are a number of things to bear in mind when refuelling your lawnmower. The most important one is: you should only refuel your mower outside and when the engine is cold and not in use.
Fuel should only be stored as directed.
Old fuel is a hazardous substance and should be disposed of as such.
Any normal petrol from a petrol station is suitable for lawnmowers – whether E 10 or conventional fuel.
Lawnmowers with 2-stroke engines require appropriate oil to be mixed with the petrol in a ratio of 1:50 – you will need to mix 50 ml of oil with every litre of petrol.
Yes, you can. However, the ethanol it contains will cause rubber hoses and seals to perish more quickly. So if you wish to use E10, you should inspect these wear parts regularly.
What type of (premium) petrol should you use for a lawnmower?
This is an easy question to answer: anything but diesel! Otherwise, you can use (premium) petrol from a petrol station to refuel your STIHL petrol lawnmower. And that includes both traditional premium petrol and E10 fuels.
However, E10 is a little hard on lawnmowers because of the ethanol it contains, as the alcohol attacks rubber hoses and seals inside the engine.
Therefore, if you use E10 fuel to refuel your lawnmower, you should inspect the rubber components of your lawnmower engine more often than usual.
However there are other factors to consider if you wish to use (premium) petrol to refuel your lawnmower: the difference in refuelling 2-stroke engines and STIHL 4-MIX® engines.
All STIHL lawnmowers feature a STIHL 4-MIX®-engine which can be refuelled using conventional (premium) petrol from a petrol station.
This means that STIHL mowers have better emissions values than comparable machines with 2-stroke engines, which require a mix of (premium) petrol and oil.
However, the benefits of STIHL 4-MIX® engines in lawnmowers can be seen well beyond refuelling, and it is considerably more pleasant to work with these machines than comparable 2-stroke engine machines. In particular this is because they run more smoothly.
Lawnmowers with 2-stroke engines should be refuelled with a mix of fuel and oil. For some models, the mixture must be mixed outside of the mower before it can be poured in.
In separately lubricated mowers, both substances are filled into the respective designated containers in the engine. The standard ratios are 1:25 or 1:50 – this means that you mix one part oil with 25 or 50 parts (premium) petrol.
Refuelling a lawnmower: Checklist
Even if you know what kind of fuel to use for your lawnmower, the way you fill it with the (premium) petrol also matters. Our lawnmower refuelling checklist provides a full overview.
| Refuelling a lawnmower: What to bear in mind |
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| Make sure you only refuel a lawnmower outside, on a level surface. |
| You should only fill the tank of your lawnmower when the engine is cold and not in use. |
| Use a damp cloth to wipe the area around the fuel tank clean after opening it. |
| Use a clean funnel to fill in the fuel. |
| Never fill the tank right to the top, as the fuel may expand; leave around 15 mm of space between the fuel and the top of the fuel tank. |
| Replace the lawnmower tank cap after you have added the fuel. |
| Caution: risk of splashing Never open the tank cap while the engine is running! |
Lawnmower refuelled incorrectly?
If you have filled your lawnmower with the wrong fuel, do not operate the mower under any circumstances. Otherwise, in the worst case, you risk damaging the engine.
We do not recommend emptying the lawnmower fuel yourself: the fuel may already have made its way inside the engine block without your noticing. Instead, you should contact a nearby STIHL dealer branch immediately. The staff there can offer you expert help.
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How to store (premium) petrol correctly
The gardening season is coming to an end and you are getting ready to put your lawnmower into storage, but there’s still plenty of (premium) petrol left in it. What should you do?
There are a few requirements to consider if you wish to store (premium) petrol. Our overview summarises the most important points for you.
| How to store fuels correctly |
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| You should never store fuel for more than three months, and E10 (premium) petrol should not be stored for more than one month. |
| Fuel should always be stored in a clean, tightly sealed canister. |
| Plastic fuel canisters should be replaced every five years because (premium) petrol attacks the plastic. |
| Metal canisters must be non-rusting. |
| Fill the canister until it is quite full and store in a cool, dry place. |
How to dispose of old (premium) petrol
If you have (premium) petrol which has been stored for some time and is no longer suitable for refuelling, you should dispose of it. But don’t forget: you cannot just throw out (premium) petrol like everyday rubbish.
It is a pollutant and a hazardous substance. You should therefore take the leftover fuel to a hazardous substances disposal point. If you are not sure where to find one, please contact your local authority.
