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Is it worth the extra cost for premium unleaded petrol?

When you fill up your car you have the choice of standard unleaded or premium unleaded (sometimes called ‘super’). Some manufacturers recommend you use premium unleaded (usually for performance cars), but do you even need to use it? How much gain do you get from using premium unleaded petrol?

What is premium unleaded?

Premium unleaded has a higher octane (RON = Research Octane Number). While regular unleaded is usually around 90-92, premium can be 95-100, depending on what brand of fuel you buy, and where in the world you buy it! Premium unleaded is more resistant to early detonation which causes a metallic pinging noise to come from the engine, and reduces the power output. Pinging is not good for your cylinders as the fuel burns early and uncontrollably, increasing the pressure in the cylinders but not transferring that pressure to the wheels.

Premium unleaded often has other chemicals such as detergents added to help clean the engine.

Should you use premium unleaded if your vehicle manufacturer recommends it?

If you primarily do low speed, low performance driving, you won’t notice any difference between premium unleaded and regular unleaded as the premium unleaded really comes into its own when using higher revs that require more performance from the engine.

Premium unleaded is better for the engine, so over time there might be negative consequences, but we couldn’t find any research that supports this, and there are a large number of factors that influence engine life and performance.

If you do want to put your foot down, though, you will almost certainly experience pinging or knocking in the engine, and a reduction in power.

Should you use premium unleaded even if your vehicle manufacturer doesn’t recommend it?

It’s perfectly fine to use premium unleaded in a vehicle that would usually run on regular unleaded. The additives in it will help clean the engine. It’s good to run a half tank of premium through the car every so often, at minimum.

You might notice a bit more responsiveness from the engine at high revs, and it’s possible that you could achieve better fuel economy, but there are so many factors that affect fuel economy (especially your driving style and the types of trips you take) that it would be almost impossible to say.

Therefore, if you have a sports car, feel free to put regular unleaded in it if you don’t plan to be driving it hard for a while. But, it’s not doing the engine any good if you do drive it hard and it exhibits pinging.

If you have a regular family car, feel free to put premium in either all the time or occasionally to help clean the engine.

Darren has owned several companies in the automotive, advertising and education industries. He has run driving theory educational websites since 2010.

Posted in Advice, Car