What The Different Octane Ratings Mean In Australia

Educational

Nov 25th, 2020

What The Different Octane Ratings Mean In Australia

First-time car owners usually struggle trying to discover what fuel terminologies such as octane ratings mean. You can hardly be blamed for this, especially if you don't have an interest in automobiles. Besides, bowsers in Australia rarely outline octane ratings and what they mean.

Understanding all octane ratings can be overwhelming. Even worse is using the wrong fuel in your car as it can damage the fuel tank and in extreme cases, even cause an explosion in the engine. As such, it is crucial to know what octane ratings mean and which rating is best for your car. Below we explore the different octane ratings and fuel types in Australia.

Petrol types (octane ratings) in Australia

When it comes to petrol types, numbers are key. These numbers differentiate petrol fuel types as they represent what is commonly referred to as octane ratings. 

Octane ratings denote a fuel’s degree of resistance to burning too early. The three broad petrol fuel types are:

  • Standard unleaded petrol (91)
  • Premium unleaded (95 & 98)
  • Ethanol-blended (E10 & E85)

Standard Unleaded Petrol (91)

The regular or standard unleaded petrol (SUP) is the most readily available fuel type in Australia. It is found in almost every bowser. Unleaded 91 has an octane rating of 91 and is cheaper than premium unleaded fuels. SUP is ideal for a petrol-run vehicle that has low-performance requirements. 

Premium Unleaded Petrol (95)

Premium unleaded petrol 95 often referred to as PULP 95 is a more efficient fuel type designed to achieve a smoother engine operation. It is not as common in Australia and is more expensive than ULP 91. PULP 95 improves performance and is thus meant for average-performance vehicles. Nonetheless, it can also be used by low-performance vehicles.

Premium Unleaded Petrol (98)

This fuel type is sometimes called Ultra-Premium unleaded petrol (UPULP) due to its high octane rating. It offers higher engine power and performance and generally has less pollution. Owing to its nature, PULP 98 is suitable for high-performance cars. It also costs more than both PULP 95 and ULP 91. 

Ethanol Blended (E10)  

E10 is a blend of 10% ethanol and 90% unleaded petrol. It is often used as an alternative to regular unleaded petrol. Ethanol has a much higher octane rating than petrol itself. Therefore, when added to the regular unleaded petrol, it increases the overall rating to 94. 

Its price varies from state to state in Australia, and while it may be cheaper than ULP, it is not as efficient. On average, it makes your car’s fuel consumption increase by 3% compared to unleaded petrol.

Ethanol Blended (E85)

E85, also known as flex fuel, is another ethanol option and is more powerful than E10. It is a blend consisting of 15% petrol and 85% ethanol. E85 is usually used in V8 supercars and other racing cars. It is also cheaper and has less pollution. E85 is hard to come by in petrol stations.

The ethanol component in this fuel increases its octane rating to between 100 and 107. Although it has high-performance characteristics, it hampers fuel economy by up to 30% due to its lower energy density.

Diesel

Diesel is an entirely different fuel that is commonly used by utes, SUVs, and many luxury European brands. Diesel is relatively easier to refine and contains more energy than petrol. Diesel is preferred because of its higher fuel efficiency and effective engine combustion process.

Is it possible to change the fuel type I use in my car?

The short answer is yes, but it will depend on your car. You can switch to a different fuel, especially if you feel that it is more fuel-efficient or will result in better performance as long as it is compatible with your car. However, as a rule of thumb, it is not advisable to use fuel with a lower rating than that recommended by the manufacturer.

Cars come with a recommended fuel type and a note that specifies the minimum octane rating that you can use. For instance, if your car manual notes PULP 95 as the recommended minimum, it is not ideal to use unleaded 91. While it doesn’t damage your engine to use a higher rated fuel, it will be less efficient and cost you more. 

What are the best fuel brands in Australia?

There are different petrol brands in Australia, and each has its downsides and upsides. Based on the average latest consumer ratings, here are the top five:

  • BP
  • Caltex
  • Coles Express
  • Woolworths
  • Eleven

Rankings typically vary from time to time based on the opinion of the consumer, so it's not unusual to see a difference in the best fuel brands. 

Point to note

Overseas and Australian octane ratings are different. Therefore, if you’re reading a car manual from overseas, keep in mind that their octane ratings are not the same as those in Australia and other parts of the world. In Australia, we use a system of research octane number, which is also adopted by most countries in Europe.

In Canada and the United States of America, the Anti-Knock Index is used as a standard. It is a numeric average of the research octane number and a second octane measurement standard known as the motor octane number. Generally, for any fuel, the anti-knock index is usually four points lower than the research octane number.


By Sam O.