Maybe you swear by one type, or perhaps you give the labels a curious side-eye when you are at the petrol station, but what exactly is the difference between high and low octane fuel?

Octane levels are what the numbers – and colours – on the petrol pumps refer to. The higher the number, the more octane there is. You will recognise 91 Unleaded as being the regular petrol that users reach for; 95 and 98 are generally seen as ‘premium’ options, with some petrol stations even offering 100.

Octane levels are important because they protect your vehicle engine from knocks and pressures that come when you start it. The spark that ignites your fuel does not do so perfectly smoothly every time, and enough knocks and pressure variations can damage your engine. A high octane level will decrease the chances of these knocks happening by producing a more regular flame and burning fuel more slowly than low octane.

But does this benefit alone make it worth the additional price you pay for premium fuel? Experts claim that higher octane levels not only improve engine performance, they also improve fuel consumption and reduce harmful emissions. However, this is not a luxury most people can afford.

Most manufacturers will recommend higher octane fuel for high-performance cars, but if all you have is a standard, reliable runner to get you from A to B, it is unlikely you have much to gain. No noticeable or measurable benefits, anyway.

Some industry members argue that boosting your regular 91 intake with a higher octane fuel every once in a while can be beneficial in supporting a healthy engine, but others dispute this, saying that there is no convincing evidence that proves this.

Although mixing fuel does not have adverse side effects to your engine, experts say you are better off in the long run just sticking to the octane recommended for your vehicle, which can be found in your vehicle’s operator manual.

So what is the bottom line about the difference between high and low octane fuel and when should you use each one? The short answer is that it depends on what type of vehicle you have and what the manufacturer recommends. Ultimately, you can simply stick with 91 and not feel too guilty that you’re not putting pricier fuel in one of your most important assets.