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Fuel types explained


To maintain your car’s peak performance for many years to come, it’s important to give it the best care possible. And that means always using the right kind of fuel. But with so many types of petrol available at the service station, how do you know which one is right for your car? 

Different engines are designed to run on different types of fuel. Using the wrong kind can reduce the performance of your vehicle — or even worse, cause some serious damage — so you should only use the type of fuel specified by your vehicle’s manufacturer. If you’re unsure what this is, consult your owner’s manual or check the manufacturer’s website.

This guide explains some of the basic differences between the main fuel types. 


Unleaded petrol causes lower exhaust emissions than leaded petrol, which ceased to be sold in Australia in 2002.[1] Using the wrong type of fuel in an engine designed for unleaded petrol can cause your car to make a knocking or rattling sound, as well as wasting energy and damaging your engine over time.

If your car runs on unleaded petrol, it’s important that you only use fuel with a high enough octane content, otherwise it may not run smoothly. Octane content is indicated by the petrol’s Research Octane Number (RON).

There are currently three grades of unleaded petrol available in Australia:

  • Regular Unleaded Petrol (ULP) has a RON of 91, the standard for most Japanese cars.  

  • Premium Unleaded Petrol (PULP) has a RON of 95 or 96, and is the standard fuel for most modern European cars.

  • Ultra-Premium Unleaded Petrol (UPULP) has a high RON of 98 and is used in more powerful engines, like those in sports cars.

You should use UPULP exclusively if ‘98-octane unleaded only’ is specified for your car. For other cars, using a higher-octane fuel than required generally won’t noticeably improve performance — but it will probably end up costing you more.


Ethanol blends

Ethanol is a biofuel produced by fermenting sugar cane, wheat or other grains. Although it produces less energy than petrol, as a renewable resource it is a more environmentally friendly alternative to oil-based fuel.[2]

E10 is ULP that contains at least 10 per cent ethanol. Most modern cars that can run on ULP can also safely use E10, but petrol containing ethanol may cause damage to cars manufactured before 1986.[3]

E85 fuel combines unleaded petrol with up to 85 per cent ethanol. Although vehicles operating on this ‘flex fuel’ are increasingly common in the United States, very few cars currently available in Australia are able to run on E85.


Diesel has traditionally been used mainly for trucks, 4WDs and heavy commercial vehicles, and over the years has gained a reputation for creating more noise and smoke than petrol. But technological advances and the transition to cleaner diesel have increased the use of diesel engines among passenger-car manufacturers like Audi.  

Biodiesel is a biofuel generated from vegetable oil or waste cooking oil. It therefore reduces the strain on non-renewable resources, as well as being less toxic than other types of fuel.[4] Any diesel engine can safely use a blend of up to 5 per cent biodiesel, while some diesel vehicles can also run on a 20 per cent blend (B20).[5]


Liquefied Petroleum Gas (LPG) blends propane and butane. It can only be used in vehicles that have been fitted with special LPG fuel systems. LPG is significantly cheaper than petrol and can extend your engine life, as well as potentially reducing exhaust emissions.[6] On the downside, the cost of converting your car to fit an LPG system can be expensive, and may reduce the power of your engine.


[1] ‘Fuel quality standards’, Department of the Environment, Commonwealth of Australia, 2013.

[2] ‘Biofuels FAQ’, NSW Office of Biofuels, 2013.

[3] ‘Ethanol: Commonly asked questions and answers’, Exxon Mobil Corporation, 2013.

[4] ‘Fuel types’,, Fubra Limited, 2013.

[5] ‘Biofuels FAQ’, NSW Office of Biofuels, 2013.

[6] ‘FAQ’, Green Vehicle Guide, Department of Infrastructure and Regional Development, Commonwealth of Australia. 


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