The facts: What is E10 fuel?

The majority of modern cars running on unleaded petrol today are compatible with E10.

Motorists should always follow their vehicle manufacturer’s advice on the recommended fuel to use in their vehicle. In some cars, this information can be found written on the inside of the fuel flap. If not there, refer to the owner’s manual or the manufacturer’s website.

High performance vehicles and older cars, particularly those built before 1986 but also any that use older technologies, such as carburetors (a device that mixes air with a fine spray of liquid fuel), shouldn’t use E10 as those engines are not designed to run on ethanol blends. Cars built with newer technologies will use a fuel injection system.

Unsure if your vehicle can use E10? Use the NSW Government's compatibility checker to find out if your vehicle is E10 ready. 

E85 is a blend of between 70% and 85% ethanol and unleaded petrol, with an octane rating of 105. It can only be used in cars that have been specifically built or modified to use it, including flexible-fuel vehicles and V8 racing supercars.

The ethanol in E10 will not dirty or damage the fuel injection system in your car if your car manufacturer has identified it as suitable to run on E10 petrol. However, ethanol is a solvent and as it runs through the fuel tank and fuel lines, it may loosen any scale or build up that is already there.

Fuel filters are generally replaced one or more times during the life of a vehicle. However, for those who are concerned about scale and build up dislodging when making the switch to E10 from other fuels, your fuel filter may need to be changed sooner than normal as a result of this initial cleansing phase, especially in older cars.

You should not use E85 in any vehicle that is not specifically designed for it.

Different types of petrol can be identified by a numbering system (91, 94, 95, 98, 105 etc), which is the octane rating of the fuel.

Octane is a measure of petrol’s resistance to igniting prematurely in the engine’s combustion chamber when the car is accelerating.

There are two types of octane rating – the Motor Octane Number (MON) and the Research Octane Number (RON). The RON is more commonly referred to, and that’s the one you see displayed on bowsers and nozzles at service stations and petrol price signs in NSW.

The higher the octane rating, the more resistant the petrol is to burning uncontrollably (‘knocking’ or ‘pinging’) before it is supposed to. Generally then, a higher octane rating results in a more complete burn of the available fuel, thereby maximizing engine efficiency.

Vehicle manufacturers design engines to be run on petrol with a minimum octane rating. You should always use petrol in your car that has an octane rating at least equal to that specified by the manufacturer. An engine’s octane requirement is usually outlined in the vehicle’s handbook, or in some cars, this information can be found written on the inside of the fuel flap. Alternatively, refer to the manufacturer’s website.

Regular unleaded petrol in Australia is RON 91, and most petrol cars sold here since 1986 were designed to run on RON 91. In turn, the majority of petrol engines designed for RON 91 are compatible with E10.

If the manufacturer has recommended that you use premium unleaded in the vehicle, this means you should fill the tank with either RON 95 or RON 98. Neither E10 (RON 94) or regular unleaded petrol should be used in those vehicles.

High-performance (or high-compression) engines are designed to take advantage of the properties of high octane fuels. They have a higher compression ratio, generating higher pressure or higher temperature in the engine than regular compression engines.

To avoid pre-ignition in high-compression engines, manufacturers of these types of vehicles generally recommend the vehicle owners use a high octane petrol. These vehicles are often not E10 compatible.

V8 racing supercars and some other cars run on E85, which is a high performance fuel with an octane rating of 105.

The typical family car sold in Australia has a regular compression engine, designed to use regular unleaded petrol (RON 91). Most of these cars can also use E10.

Unsure if your vehicle can use E10? Use the NSW Government's compatibility checker to find out if your vehicle is E10 ready. 

E10 is a blend of regular unleaded (RON 91) petrol and between 9% and 10% ethanol. Blending the ethanol at this ratio increases the RON to 94.

Prescribed by the Commonwealth Government, the Fuel Quality Standards set the technical specifications that a fuel needs to meet to be described as ‘premium unleaded petrol’.

Relevant technical specifications include the fuel’s Research Octane Number (RON), Motor Octane Number (MON) and sulfur levels. A premium fuel must be at least RON 95. More information about the Standards is available on the Commonwealth Department of Environment and Energy website.

Find your nearest E10 pump.

At the pump, E10 is generally the cheapest petrol per liter. Because the energy provided by the ethanol is less than the energy provided by pure petroleum, E10 has around 3% less energy than the equivalent amount of RON 91 petrol.

On average, this can translate to an increase in fuel consumption of around 3%, which has about the same effect on fuel consumption as driving on tyres with inadequate air pressure.
Fuel economy is influenced by a range of factors including how well your vehicle is maintained, how much you use the air con, road conditions and how efficiently you drive.

The story of E10 gets a bit more complicated when considering which type of petrol to use in other engines such as garden equipment (mowers, whipper snippers), generators, marine engines such as outboard motors and aircraft.

You should always refer to the owner’s handbook or ask the manufacturer or distributor whether E10 is suitable for the engine you’re using.

Ethanol-blended fuels are generally not recommended for marine engines due to the danger of water contaminating the fuel. More information about the use of E10 in marine engines is available on the Roads and Maritime Services website.

Ethanol-blended fuels are not suitable for aircraft. You can find out more from the Civil Aviation Safety Authority website.

Back in the early 2000s, the Fuel Quality Standards Act 2000 was introduced to govern fuel standards in Australia. At the time, these regulations did not cover the use and labelling of ethanol in petrol.

In 2002, NSW Fair Trading began receiving complaints from consumers that petrol containing up to 20% ethanol was causing engine damage. With no legally enforceable requirements around quantity and labelling of ethanol in petrol motorists didn’t know exactly what they were buying and had no way to prove that ethanol was to blame.

Many of the worst impressions about ethanol being a ‘dirty’ ‘cheap’ or ‘risky’ fuel that appeared to damage engines, probably date from this time.

More history on E10.

It's not just Australia that is embracing biofuels as an alternative to traditional fossil fuels. Ethanol is the most widely used biofuel in the world and over 64 countries have active programs promoting the use of ethanol as a mainstream fuel, including the United States, China, Brazil, Canada and the European Union as well as countries in Latin America, South East Asia and Africa.

"It is time the governments of the world … together with industry and consumers … put the energy system on track to a sustainable and secure energy future. We owe it to our economies, our citizens and our children." Maria van der Hoeven, Executive Director, IEA.

Australia is a member of the International Energy Agency (IEA). The IEA has reported that between 2000 and 2013, world biofuel production increased sevenfold. Around the world, increased production and use of biofuels is an important part of achieving a clean energy future.