Is premium fuel any better?

When you pull up to the pump at a petrol station, sometimes it can take a second to remember what fuel you usually put into your car. With so many - often similarly named - options, you may be left wondering: is there really much difference?

Most of us know that putting diesel in a petrol car, or vice versa, is never a good idea. But when it comes to the different types of petrol fuels on offer, what’s really the difference? Is premium any better? And can putting the wrong fuel in damage your engine?

Let’s find out.

What is premium fuel?

The difference between premium fuel and standard fuel comes in the form of the octane number. The octane number is the standard measure for engine performance, and describes a fuel’s stability. The rating is based on the pressure at which a fuel will combust in a testing engine, or the fuel’s ability to withstand compression without detonating.

A regular unleaded fuel has an octane number of around 95. Compare this with a premium fuel, such as BP’s Ultimate Unleaded or Texaco’s Supreme Unleaded, and you’ll see these have an octane number of 97.

The makers of premium fuels insist that there are noticeable differences to using these higher quality offerings, from removing dirt from inside the engine to helping everything run more smoothly. But they do come with an increased price tag.

Can all cars take premium fuel?

As we mentioned right at the beginning of this article, most drivers have had drilled into them the dangers of putting diesel into a petrol car, or the other way around. But fortunately, the same doesn’t quite apply when it comes to premium or standard fuels.

If you’re not sure what fuel your car should take, then have a read through your handbook. You should find advice on the recommended octane rating necessary to keep your engine working at its best there. You might also spot a sticker giving you information about the right fuel for your car around your fuel cap, or on the inside of the flap to access your fuel cap.

While all cars have a recommended octane rating, putting premium fuel in instead of standard, or the other way round, is unlikely to do your engine any harm. You’re also unlikely to encounter any issues if you mix the two; for example, if you top up with standard fuel while there’s still premium fuel in your tank.

However, if your handbook recommends a higher octane fuel, and you fill up using a lower-octane option than is recommended, then this could result in engine damage over the long term.

So, is premium fuel better?

There are undoubtedly benefits to using premium fuel in your car. The higher the octane number, the more power gets delivered to your engine – meaning that you’re really making the most of every drop of petrol. It also, theoretically, results in a healthier engine over time, due to later ignitions from the fuel itself.

Pair this with the added benefits many premium brands have included, such as cleaning additives that help to keep the engine clean, or lubricating agents, and it’s undeniable that when you look at pure chemistry, premium fuel is superior.

However, while there is evidence to show that these perks are undoubtedly effective, there have been studies that show that these additives are equally as effective even if you only use premium fuel occasionally. So, for example, if you fill up with premium fuel once every five times, you’re still likely to see the benefit of perks such as engine cleaning and added lubrication.

What’s most important to remember is that some cars run perfectly on standard unleaded fuel, whereas others require the additional efficacy of higher octane, premium versions. The key is to check your car’s handbook for guidance on getting the right fuel for your car.