Demystifying RON: Understanding Octane Ratings and Fuel Choices

Demystifying RON: Understanding Octane Ratings and Fuel Choices banner

If you've ever glanced at a petrol pump or read a car review, you've likely encountered the term "RON." But what does it mean, and why does it matter? Let's dive into the world of Research Octane Number (RON) to demystify this essential aspect of fuel selection.

What is RON?

RON stands for Research Octane Number, which is a measure of a petrol's octane rating. In Australia, petrol is available in various octane ratings, with premium unleaded offering the highest RON. Here's a breakdown of common octane ratings:

  • 98 RON: Premium unleaded
  • 95 RON: Premium unleaded
  • E10: 94 RON
  • Standard 91: Unleaded
  • E85: 107 RON (racing blend by United fuels)

Understanding Octane Ratings

The octane rating indicates a fuel's ability to resist premature detonation, also known as engine knock. This knocking sound occurs when fuel detonates too early, before the spark plug ignites it. The compression ratio of the engine plays a significant role in determining the likelihood of engine knock.

  • Compression Ratio: This describes the volume of the cylinder when the piston is at the bottom of its stroke compared to the top of its stroke. Higher compression ratios result in greater thermal efficiency, producing more power and better fuel economy.
  • High RON Fuel: Fuels with higher RON combust at hotter temperatures and under greater pressures, making them suitable for high compression ratio engines. Premium 98 RON unleaded offers the greatest knock resistance.

Choosing the Right Fuel

While older cars may accept lower octane fuels, newer vehicles with high compression ratio engines, especially turbocharged ones, prefer 95 or 98 octane premium unleaded. Electronic fuel injection systems can detect engine knock and adjust ignition timing, but this may impact performance and fuel economy.

Premium Fuel and Engine Cleaning

Fuel companies often claim that premium fuel cleans engines, but it's not a necessity. Modern vehicles are equipped with fuel filters to prevent impurities from damaging components. Adhering to manufacturer service intervals and occasionally driving at ideal operating temperatures are better ways to maintain engine cleanliness.


Understanding RON and octane ratings is crucial for choosing the right fuel for your vehicle. While higher RON fuels offer better knock resistance, following manufacturer recommendations ensures optimal performance and longevity. 

Copyright © 2024. All Rights Reserved by Tynan Motors. LMCT MD 7483
Powered By Dealer Studio