In brief: Your lawn mower needs standard unleaded petrol with an octane rating of 95 (E5 or E10). Use the fuel neat for 4-stroke engines. For 2-stroke engines, mix the petrol with special 2-stroke oil in the ratio specified by the manufacturer. Avoid alkylate petrol unless you are storing the mower over winter or using it in enclosed spaces.
What Petrol Does a Lawn Mower Need? The Right Fuel
Choosing the wrong petrol can ruin your lawn mower within a single season. Modern engines are precision machines. They are sensitive to contaminated or unsuitable fuel.
We explain the differences between 2-stroke and 4-stroke engines, the importance of octane ratings and provide clear recommendations. This will help protect your investment in garden tools.
4-Stroke vs. 2-Stroke: The Fundamental Difference
The engine design determines which fuel you need. Do not confuse the two types. The consequences can be serious.
How a 4-Stroke Engine Works
4-stroke engines are the standard design in most lawn mowers. They have a separate oil circuit. The name describes the four operating stages: intake, compression, power and exhaust.
Here, you fill up with pure, unmixed fuel. The engine oil is held in a separate reservoir. It must be changed regularly.
„A 4-stroke engine is like a car engine in miniature. It needs two separate fluids: petrol for combustion and oil for lubrication. Mixing oil into the petrol destroys the catalytic converter and fouls the spark plug.“
How a 2-Stroke Engine Works
You often find 2-stroke engines in lightweight equipment such as brush cutters, clearing saws and small leaf blowers. They combine intake and compression as well as power and exhaust in just two strokes.
There is no separate oil circuit. Lubrication is provided by the oil mixed into the fuel. This oil-petrol mixture burns inside the cylinder.
Important note
Never fill a 2-stroke engine with pure petrol. Without added oil, the engine runs dry. Within just a few minutes, this causes the piston to seize – resulting in irreparable engine damage. Read the operating instructions and mix the fuel exactly as specified.
Octane Ratings: What Do 95, 98 or 102 Mean?
The octane rating (RON) measures how resistant petrol is to knocking. A knocking engine operates inefficiently and can be damaged. A low octane rating is perfectly adequate for lawn mower engines.
Super E5 (95 Octane) – The Standard Recommendation
Unleaded petrol with 95 octane and a maximum of 5% ethanol is the ideal fuel for almost all lawn mowers. The engines are designed for it. Higher octane ratings provide no performance benefit.
You simply spend more money. Pay attention to the ethanol content. E5 is well tolerated.
Super E10 (95 Octane) – Use with Caution
E10 contains up to 10% ethanol. This bioethanol is more aggressive towards seals, hoses and metal parts. It also attracts moisture.
E10 is usually approved for modern equipment from around 2011 onwards. Check the manufacturer's specifications. For older mowers and all 2-stroke engines, E5 is the safer choice.
Pro tip
Always buy petrol for your lawn mower at a petrol station, not from the canister section of a DIY store. Fuel from petrol stations has guaranteed quality and higher turnover, which means it is fresher. Pour it into an approved blue petrol can.
Super Plus (98 Octane) & Ultimate (102 Octane) – Unnecessary
These fuels are designed for high-performance engines in sports cars. Your lawn mower cannot make use of the higher octane rating. The combustion process will not become more efficient.
You pay extra for no benefit. Stick with Super 95.
The Mixing Ratio for 2-Stroke Engines
The correct mixture is vital for your 2-stroke engine. Too little oil causes wear. Too much oil fouls the spark plug and exhaust.
How to Mix It Correctly
Use only special 2-stroke engine oil. It is optimised for combustion in the mixture. Automotive or 4-stroke engine oil produces too much soot.
Typical mixing ratios are 1:50 or 1:25 (1 part oil to 50 or 25 parts petrol). A measuring cup or mixing bottle ensures accuracy. Do not guess.
„The biggest problem with 2-stroke mixtures is inaccuracy. A little more or less oil may seem irrelevant. But over time, an incorrect mixture causes loss of power, increased fuel consumption and ultimately engine damage. Precision pays off.“
Ready-Mixed Fuel – Convenient but Expensive
Specialist retailers sell pre-mixed 2-stroke petrol in cans. It is ideal for occasional users who do not want to store entire canisters.
The price per litre is significantly higher. For regular use, mixing the fuel yourself is worthwhile. For garden work with several machines, a canister is the more economical solution.
Alkylate Petrol: The Premium Fuel
Alkylate petrol is a highly refined fuel that is almost free of sulphur and aromatics. It burns very cleanly, producing minimal soot and odour.
Advantages of Alkylate Petrol
Its storage stability is the greatest advantage. It remains usable for years without losing quality. It is ideal for winter storage.
As it gives off hardly any harmful fumes, it is perfect for use in enclosed spaces, garages or greenhouses. It is also the better choice for your health.
Disadvantages and Costs
Alkylate petrol costs around three times as much per litre as standard Super. For weekly lawn mowing outdoors, the additional cost is difficult to justify.
Engine performance remains the same. You are paying for cleanliness and longevity – both of the equipment and of the fuel itself.
Additional advice
Fill the tank with alkylate petrol for the final mowing session before winter. This prevents deposits from forming in the carburettor during storage. Your mower will start immediately again in spring. This is a worthwhile investment that saves you expensive cleaning.
Fuel Storage and Shelf Life
Petrol gets old. The ethanol content in E5 and E10 in particular causes chemical changes. Incorrect storage ruins the fuel and puts your equipment at risk.
How to Store Petrol Correctly
Always store canisters in a cool, dark and dry place. A garden shed or well-ventilated garage is suitable. Protect the canister from direct sunlight.
Use only approved containers. Seal them tightly so that no oxygen can enter and evaporation remains minimal. Label the canister with the purchase date.
When Petrol Goes Bad
Standard Super E5/E10 is no longer fresh after around 3 months. After 6 months, its quality is often so severely impaired that you should no longer use it.
You can identify old petrol by its dull smell and possible discolouration. It forms rubbery deposits. These clog the fine jets in the carburettor.
Practical Tips for Refuelling
Clean refuelling helps protect against contamination. Dirt in the fuel tank is a common cause of problems.
Before Refuelling: Safety Comes First
Always let the engine cool down completely. Never refuel while the engine is running or hot. Place the lawn mower on a level surface.
Keep a fire extinguisher or sand nearby. Do not smoke. Work outdoors or in a very well-ventilated area.
While Refuelling: Cleanliness Matters
Use a funnel with a strainer. This catches coarse dirt and dust. Do not fill the tank right to the top.
Leave around 2 cm of air space. This allows room for the fuel to expand. Close the fuel cap immediately and firmly.
After Refuelling: Clean Up Any Spills
Wipe up spilled petrol immediately with a cloth. Dispose of the cloth safely, not in household waste.
Only start the mower after moving it away from the petrol station. This helps you avoid petrol fumes near the refuelling area.
Suitable Equipment for Your Garden
Choosing the right fuel is part of proper equipment care. A powerful, suitable tool makes the work easier. In our range, you will find reliable helpers.
The
is a versatile helper for hard-to-reach areas. Its 2-stroke engine requires a petrol-oil mixture. Its power makes it the ideal partner for maintaining your property.
For precise hedge trimming, the
is an excellent choice. Its 4-stroke engine runs on pure petrol and offers smooth operation and lower fuel consumption. Maintenance is simple.
The
is a powerful grass trimmer for large areas and tall grass. It also uses a 4-stroke engine. For maximum performance, pay particular attention to using fresh, low-ethanol fuel.
Conclusion: Clear Rules for Choosing the Right Fuel
Choosing the right petrol is not rocket science, but it does require care. Follow the manufacturer's specifications. Always distinguish clearly between 2-stroke and 4-stroke engines.
For everyday use, choose fresh Super E5. Remember the winter break and either empty the tank or use alkylate petrol. With the right care and suitable fuel, your lawn mower will serve you for many years.
Invest the few minutes needed to refuel correctly. You will save yourself expensive repairs and trouble the next time you start the mower.
Frequently Asked Questions
- Can I use E10 petrol in my lawn mower?
- For most modern lawn mowers with a 4-stroke engine built from 2011 onwards, E10 is not usually a problem. Check the operating manual or rating plate. For older equipment and all 2-stroke engines, unleaded Super E5 (up to 5% ethanol) is the safer choice, as ethanol can damage materials and cause water separation in the tank.
- What is the difference between 2-stroke and 4-stroke petrol?
- 4-stroke petrol is pure, unmixed petrol (E5/E10). 2-stroke petrol is a mixture of petrol and special 2-stroke oil. A 2-stroke engine needs the oil in the fuel for lubrication. Always mix it in the exact ratio specified by the manufacturer (e.g. 1:50). Never use pure petrol in a 2-stroke engine – this can cause the piston to seize.
- How long can I store petrol in a lawn mower?
- Regular petrol containing ethanol (E5/E10) starts to deteriorate after 4-6 weeks. It forms resins and gum that can block the carburettor and fuel lines. Before the winter break, empty the remaining fuel or use ethanol-free alkylate petrol, which remains stable in storage for up to 5 years. A fuel stabiliser can also extend its shelf life.
- Why won't my lawn mower start after winter?
- The most common cause is old, degraded petrol in the carburettor. Ethanol attracts water, which causes corrosion and can block the carburettor. Before the winter break, empty the tank or run the mower dry. Use ethanol-free petrol for the final tankful. Regular maintenance helps prevent this.
- Is expensive alkylate petrol worth it for a lawn mower?
- Alkylate petrol is almost free of harmful aromatics, burns more cleanly and remains stable in storage for a long time. It is ideal for storing equipment over winter and for use in garages or greenhouses. For regular use in the garden, however, standard Super E5 is perfectly adequate and more affordable. The investment is worthwhile for overwintering or when using sensitive equipment.