What Is an Octane Rating?
Walk into any fuel station and you'll see numbers on the pump: 92, 95, 98, or even higher. These numbers refer to the fuel's octane rating — specifically, the RON (Research Octane Number). But what does this number actually mean, and does choosing a higher octane fuel make a real difference to your car?
The Science Behind Octane
Octane rating measures a fuel's resistance to knocking (also called pinging or detonation). Knocking occurs when the fuel-air mixture in a petrol engine ignites prematurely or unevenly, before the spark plug fires. This creates a characteristic knocking sound and, over time, can damage engine components.
A higher octane rating means the fuel is more resistant to this unwanted pre-ignition. Engines with higher compression ratios — typically performance or turbocharged engines — are more prone to knocking and therefore require higher-octane fuel to operate correctly.
Common Octane Grades Explained
| Grade | RON | Typical Use |
|---|---|---|
| Regular | 92 | Older or basic engines designed for standard fuel |
| Mid-grade / Standard | 95 | Most modern passenger vehicles |
| Premium / Super | 98+ | High-performance, turbocharged, or premium engines |
Does Premium Fuel Improve Performance?
This is one of the most common questions at the pump. The honest answer is: it depends entirely on your engine.
- If your car's manufacturer specifies 95 RON, using 98 RON will not meaningfully improve performance or economy — the engine is not designed to take advantage of it.
- If your manufacturer requires 98 RON, using lower-grade fuel can cause knocking and may activate engine protection systems that reduce power output to compensate.
- Some modern engines with adaptive ignition systems can run on lower octane fuel safely but will deliver better performance when given the recommended grade.
Premium Fuels: Additives and Detergents
Beyond octane rating, many premium fuel products — including premium grades at major fuel networks — contain additional detergent and cleaning additives. These are designed to:
- Keep fuel injectors clean and functioning efficiently
- Reduce carbon deposits in combustion chambers
- Potentially improve combustion efficiency over time
The benefits of these additives are real but gradual — you're unlikely to notice an immediate dramatic difference. Over tens of thousands of kilometres, however, keeping injectors clean can help maintain fuel economy and engine smoothness.
How to Find the Right Fuel Grade for Your Car
- Check your vehicle owner's manual — it will specify the minimum and recommended RON.
- Look inside the fuel filler cap — many manufacturers print the required fuel grade there.
- When in doubt, use the grade recommended by the manufacturer. Never use a lower grade than specified.
- If you've accidentally used the wrong grade, avoid hard acceleration and consult your dealer if knocking occurs.
The Bottom Line
Octane rating is not a measure of fuel quality in a general sense — it's a specific measure of knock resistance. Using the correct octane grade for your vehicle protects your engine and ensures it operates as designed. Going higher than needed offers no practical benefit for most drivers, while going lower than required can cause real harm to performance engines.