What petrol should I use for my car?

what petrol should I use for my car

We get this question a lot dealing with used cars – we’re constantly seeing car manufacturers making newer models of cars that run differently to their older counterparts with all the advances in technology.

So which petrol should I use, and how exactly does it change how the car runs?

Firstly, let’s start with some of the more common options you have to fill your car. There are generally a few types of petrol on offer when you head to your local service station:

  • Standard unleaded 91-octane
  • Premium 95-octane unleaded
  • Premium 98-octane unleaded

The Octane or ‘RON’ (Research Octane Number) is a measure of how much heat and pressure a type of fuel can withstand before igniting. Essentially, the numbers 91, 95 and 98 indicate how well the fuel can resist burning too early inside a cars’ engine. This is why higher performance cars with more complex compression ratios require higher octane fuel, such as Premium 95 and Premium 98.

1. Standard unleaded 91-octane

This is the most common type of fuel in Australia – Unleaded 91 (or ULP 91) can be found at almost every petrol station.

2. Premium 95-octane unleaded

Premium unleaded 95 petrol (PULP 95) is an unleaded fuel designed to be more fuel efficient, as newer model engines that are validated with this fuel.

3. Premium 98-octane unleaded

Sometimes referred to as ‘Ultra Premium unleaded petrol’, premium 98-octane (ULP 98) fuel is the highest octane unleaded fuel, and provides an even higher engine power and performance. This petrol is generally best-utilised by high performance cars.


So can a car that normally runs on Premium 95-octane unleaded, safely run on Standard 91-octane unleaded petrol?

You can, but it would be wise to stick to what’s recommended by the cars’ manufacturer.

If 91-octane petrol is used in a 95-octane petrol recommended car, you run the risk of pre-igniting or ‘knocking’ in amongst the car’s engine – this is when the petrol combusts too early and pushes down against a piston. This can cause serious damage to an engines internal parts.

Modern engines have knock sensors fitted, which listen to the engine and are there to detect pre-ignition (knocking). Using a lower octane petrol in a 95- or 98-octane car also has the side effect of lower performance and a change in your fuel emissions.

If the manufacturer recommends that your car should be running on 95-octane, then you should use that fuel. This recommendation is made as the vehicles undergo a validation process for performance, fuel consumption and exhaust emissions – which is always done using a specific fuel. The recommended octane is usually displayed on the inside of your vehicle’s fuel flap, and will also be listed in the owners’ handbook. A car will always perform better on the recommendation from the manufacturer.

However, you can use fuel the other way round – putting 95-octane in your car if you car usually runs on 91. It won’t do too much in terms of the performance of the car, and it may not always be worth the extra cost!

So to summarise, you can put 91-octane petrol in a 95-octane car?

Yes you can – but only if absolutely necessary!

It’s not the end of the world (or your car) if it’s supposed to run on 95-octane petrol and you put 91-octane in the fuel tank instead – as long as it isn’t done often and gets refilled with the recommended 95- or 98-octane in the next tank. Keeping to the recommended fuel from the manufacturer will result in your car having a longer life.


Questions around fuel are great questions to ask when purchasing your next car. It’s all about finding the right fit car for you and your family! Check out our current range here, and even book yourself in for a test drive today!

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