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The Best Fuel for Your Car | comparethemarket.com.au

4 min read
15 May 2014

Once upon a time, it was as easy as ‘put fuel in your car’ and hit the open road but these days, you may feel boggled by the number of fuel options out there – unleaded, premium unleaded, high octane, bio fuel, ethanol blend, diesel, bio-diesel…the list goes on and on and may leave you baffled at the bowser. It would be foolish (although excusable for the car non-enthusiast) to labour under the delusion that ‘fuel is fuel’. Choosing the wrong fuel for your vehicle could, at best, reduce your car’s performance and at worst, blow up your engine and cause thousands of dollars’ worth of damage.

You can check the type of fuel your car needs on the inside flap of your fuel tank cover or on the fuel cap. It may indicate unleaded only, premium unleaded only, high octane only, diesel only, ethanol only, autogas only etc. If you can’t find the fuel type near your gas cap, check the owner’s manual for your vehicle; the manufacturer will specify the best type of fuel for your vehicle.

Car manufacturers are smart. They put lots and lots of money into research and development. They know exactly which type of fuel will help your car perform to its optimum level and keeps your engine running smoothly for years to come, so stick to their recommendation!

Types of Fuel


Most consumer cars are petrol powered. Petrol comes in a few different varieties, including standard unleaded, premium unleaded and high octane. Cars manufactured pre-1986 ran on a form of petrol containing tetraethyl lead (also known as leaded petrol); leaded petrol was phased out in Australia in 2002. Petrol powered cars now run on standard unleaded, premium unleaded and high octane – you may be used to seeing this at the pump in numbers so: standard (91 octane), premium (95 octane) and high octane (98 octane).

As a general rule, newer cars perform better on higher octane fuels; most high performance and European cars will indicate a minimum of 95 octane fuel for efficiency and performance. In older vehicles, the benefits are less certain, although most fuel companies maintain that higher octane fuel means less wear and tear on your engine components due to lower uncontrolled combustion rates.

In Australia, pure 91 octane fuel is in the processed of being replaced with E10 fuel, which is 10% ethanol based and offers reduced carbon emissions. Most older cars that use standard petrol will not be equipped to accept E10 fuel and will need to opt for premium unleaded to avoid damaging their engines.

Now, you can ‘octane up’ but you can’t ‘octane down’ – meaning that if your manufacturer indicates standard unleaded, you can still choose to put in premium or high octane fuel. It will not hurt your car to go for a higher octane fuel – however, the higher the octane the higher the price tag, so it may hurt your wallet! NEVER use a lower octane fuel than the minimum indicated by your manufacturer or you risk doing serious damage to your vehicle.


Diesel is a popular choice for SUVs and work utes and is becoming increasingly popular for luxury European brands as well. Traditionally, diesel engines have been more robust than petrol engines, and recent advances in technology have also made them a more environmentally friendly option than many petrol powered vehicles. However, this increase in popularity has also lead to an increase in ‘mis-fueling’ (i.e. putting petrol in a diesel only vehicle or vice versa). Mis-fueling is a serious no-no. If you accidentally put petrol into your diesel fuelled car – DO NOT TURN IT ON. You will need to have the tanks drained and the engine flushed out or you will ruin your engine.

There are also bio-diesel and premium diesels available on the market, so make sure you read the manufacturer’s guidelines for your vehicle and check what’s in the premium/bio-diesel as your engine may not be designed to work with some of the premium additives and ethanol mixes on the market.


Autogas, also known as liquid petroleum gas (LPG), is a mixture of propane and butane and is considered a more eco-friendly fuel type. Most standard combustion engines can be converted to auto gas with conversions costing a few thousand dollars.

The Final Word

Whatever your car, make sure you choose the right type of fuel to keep the engine purring; moderated driving and regular maintenance will help keep your car in tip-top condition. Also, check out comparethemarket.com.au’s fuel comparison tool in the Simples app, so you can track down the best prices in your area.

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Written by Compare the Market

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