During summer 2021 the fuel companies and the government have changed the ethanol content of standard 95 octane unleaded petrol sold at the pumps from 5% ethanol content to 10% ethanol content. They will still offer the lower 5% ethanol content fuel but only in the more premium grade super unleaded fuel. These will be identifiable on the pump handle with E10 or E5 labelling (as shown on the top image).
Ethanol effects in garden machinery is nothing new and even the 5% ethanol content has been causing issues in the past few years as the ethanol in the fuel goes stale (like milk), but the 10% rise in ethanol content in unleaded pump fuel could cause the effects of unleaded fuel going stale to increase and cause the damage to increase on fuel lines and carburettor components like rubber gaskets, diaphragms and ethanol deposits will block the jets up inside the carburettor. Ethanol will also degrade the aluminium casting of a metal style carburettor.
This fuel change will also affect other small petrol engine machinery like outboard boat engines, petrol generators, construction equipment using petrol engines and classic cars, old motorbikes and scooters and other vehicle petrol engines built before the year 2000. Most new small engines built after the year 2000 fitted to garden machinery, generators and construction equipment will run on the E10 fuel, but manufacturers recommend the new standard E10 fuel isn’t stored or left in the fuel system of a engine for more than “30 days without a fuel stabiliser” and the E5 super unleaded isn’t stored or left in the fuel system of a engine for “90 days without a fuel stabiliser”.
If you are using your garden machinery or other equipment for daily use and long running periods (contractor, forestry and grounds maintenance use), E10 or E5 can be used, but it is still recommended by the manufacturers to use a suitable fuel stabiliser or oils containing fuel stabilisers (two stroke machinery oils) to keep your equipment running at its top performance and to reduce machinery downtime.
How to prevent the ethanol affects to garden machinery?
To keep your petrol-powered garden machinery operating at its best and avoid issues with ethanol you can use the following items.
- Fuel stabilisers such as “Briggs and Stratton Fuel Fit” which can be added to E10 and E5 unleaded fuel to reduce the effects of the ethanol going stale, damage to your engine and fuel system. They will also improve starting of your engine.
- For two stroke petrol machinery (chainsaws, strimmer’s, hedge cutters etc.) you can use two stroke oils which have a fuel stabiliser blended into the oil, like “Stihl HP Super” and “Stihl HP Ultra” which both contain a fuel stabiliser. Both oils have better lubrication properties compared to the standard two stroke oils sold on the market including Stihl HP (the red oil) and both HP Super and HP Ultra create less exhaust smoke and are ideal for machines being used for long working hours. There are also various other machinery manufacturers and oil manufacturers who provide a two stroke oil with added fuel stabiliser in the oil.
- Change over to a Alkylate based fuel. Alkalyte based fuels such as ASPEN 2 & 4, Stihl’s MotoMix and Moto4plus fuels, contain no ethanol so the fuel system isn’t damaged, they reduce exhaust emissions from your engine fitted to your garden machinery, reduce engine wear and have a shelf storage life of 3-5 years. ASPEN 4 and Stihl Moto4plus fuels are suitable for all 4 stroke petrol engines fitted to lawnmowers, ride on mowers, tillers/rotorvators, generators and other equipment with a small petrol engine fitted. ASPEN 2 and Stihl MotoMix fuels are suitable for Stihl and other two stroke engine powered equipment and are premixed to 50:1 ratio with the alkalyte non ethanol fuel and a premium grade two stroke oil so no mixing is required.


