Australia is a nation that loves to drive.

In the 2017-18 financial year, we consumed a total of 34,170 mega litres of fuel, with the average passenger vehicle driving around 12,600km per year.i With all this time on the road, it’s no surprise that drivers generally want to find the fuel that can get them the most bang for their buck.

But is the cheapest fuel necessarily the best fuel for your car? Let’s unpack what those numbers mean for different types of petrol and which fuel suits your car.

What is an octane rating, and why does it matter?

When filling up your car, have you ever wondered what those numbers 91, 95 or 98 mean? They represent your fuel’s octane level.

The Research Octane Number (RON) determines how much resistance fuel has to ignite in your engine. If it burns too quickly in an engine, it can cause pinging, which can ultimately damage vital parts of your car. The higher the octane number is, the more resistant the fuel is to pinging in your engine.

For this reason, it’s recommended you fill high-performance cars with higher octane fuels, such as 98 premium unleaded petrol, since these cars are more likely to burn fuel consistently at higher temperatures than regular cars. Otherwise, regular passenger cars that don’t have high-performance requirements should generally be fine running on regular unleaded.

Types of car fuel

Regular unleaded petrol (91)

Generally the most readily available type of fuel in Australia, regular unleaded petrol has an octane rating of 91. While it doesn’t have the octane rating of premium unleaded fuels, regular unleaded is cheaper at the bowser, making it suitable for petrol-run cars that don’t have high-performance requirements.

E10

An alternative to regular unleaded petrol, E10 is a fuel that includes a 10% blend of ethanol with 90% ULP. Ethanol generally has a higher octane rating than petrol, which means that adding it to ULP increases its overall rating to 94.

Depending on where you live, E10 may be cheaper at the bowser than ULP. However, it generally isn’t as fuel efficient as regular unleaded, as your car’s petrol consumption may increase by around three per cent when using E10.ii

Premium unleaded petrol (95 and 98)

Available in octane ratings of 95 and 98, premium unleaded is suited to high-performance cars and is significantly more expensive per litre than regular unleaded. While they can be used in cars that commonly run regular unleaded, the difference in performance might not be worth the extra cost.

E85

Also known as ‘Flex Fuel’, E85 blends 85% ethanol with 15% unleaded and is generally used in professional racing due to its high-octane rating of 105. In fact, as of the 2009 season, all V8 Supercars have converted to the ethanol blend.iii

While it’s more environmentally friendly and may be cheaper than 98 petrol at the pump, E85 is only available at select service stations. Also, older engines might have to be converted to be compatible with E85.

Diesel

Diesel is a common fuel 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 advances in technology have also made them a more environmentally friendly option than many petrol powered vehicles.

There are also biodiesel and premium diesel fuels available on the market. As such, make sure you read the manufacturer’s guidelines for your vehicle. Also, it’s a good idea to 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.

Liquefied petroleum gas (LPG)

LPG, also known as Autogas, is a mixture of propane and butane and is generally considered one of the more eco-friendly fuel types. Most standard combustion engines can be converted to LPG with conversions costing a few thousand dollars. If you’re considering changing your car over to Autogas, visit our LPG conversion page.

How do I know what fuel my car takes?

Your car’s owner’s manual should outline the recommended fuel for your vehicle. This information can also often be found on the inside of the fuel cap.

So, if the label on the cap says ‘unleaded petrol only’, it can run on regular unleaded petrol or higher octane fuels. Conversely, ‘premium unleaded fuel only’ signifies that your car should only be filled with fuel above 95.

Here’s the recommended fuel for some of the top-quoted car models through our car insurance comparison service:

Make, model and yearRecommended fuel
Toyota Corolla 201391 or higher octane petrol (95 and 98)
Mazda 3 201391 or higher octane petrol (95 and 98)
Holden Commodore 201191 or higher octane petrol (95 and 98)
Toyota Camry 201391 or higher octane petrol (95 and 98)
Toyota Hilux 201391 or higher octane petrol (95 and 98)
Ford Falcon 201091 or higher octane petrol (95 and 98)
Hyundai I30 201391 or higher octane petrol (95 and 98)
Volkswagen Golf 201895 or 98
Mitsubishi Lancer 200991 or higher octane petrol (95 and 98)
Toyota Yaris 200891 or E10
N.B. This should only be used as a guide. Please consult your owner’s manual for information about your car’s fuel requirements.

What if I put the wrong fuel in my car?

Misfuelling with diesel or petrol

Filling up a diesel engine with petrol – and vice versa – can seriously damage your car. Some of the biggest differences between the fuel types is their densities and the temperature at which they ignite.

For example, diesel is thicker and ignites at higher temperatures. So, putting petrol into a diesel tank could lead to major problems for your engine, since it ignites at lower temperatures. Conversely, putting diesel in a petrol engine also causes issues, since it can go unburned and may seep into your exhaust system.

Always be careful when fuelling your car. On top of damaging your engine, misfuelling may also void your warranty and generally won’t be covered by your car insurance.

Steps you can take after misfuelling

If you accidentally put the wrong fuel in your car, you should take the following steps to help avoid engine damage:

  1. Don’t start your car. To limit the damage, leave your car where it is.
  2. Inform your station attendant. Unfortunately, you’ll still have to pay for the fuel, regardless of whether it’s the right type for your engine. Notifying the attendant will also inform them of your issue and why your car isn’t moving from the bowser.
  3. Call roadside assistance. Don’t attempt to move your car until they arrive. They can tow your car to the nearest mechanic, who can begin to drain the fuel from your tank.

If you’ve recognised a fuelling error while driving, safely pull over and call roadside assistance.

Find great fuel prices near you

Now that you’ve figured out which fuel is right for your car, why not ensure you aren’t spending too much at the bowser? Through our fuel comparison service, you can find some of the cheaper petrol stations near you, which may save you money the next time you go to the bowser. Just enter your postcode and the fuel you need, and we can compare prices in seconds.

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Sources

[i] Australian Bureau of Statistics. 9208.0 – Survey of Motor Vehicle Use, Australia, 12 months ended 30 June 2018.
[ii] E10 Fuel for Thought. The Facts.
[iii] United Petroleum. E85 Race Blend.