What does premium fuel actually do, and is it worth it?
Pulling up to the petrol pump, drivers are invariably confronted by 3 options: unleaded, premium unleaded and diesel. It’s a simple choice, but then again is it? Obviously, a diesel-engine vehicle will need filling-up with diesel. A petrol-engine vehicle will need filling-up with unleaded or premium unleaded and therein lies the quandary. Why should I fill-up with premium unleaded petrol, what does it actually do, are there any benefits and is it worth paying more?
Premium, Super, Ultimate
The premium part of unleaded fuel generally refers to a higher research octane number (RON). The octane number is a standard measure of the performance rating of an engine fuel. A higher octane number enables the fuel to withstand more compression before being ignited. In general terms, fuel with a higher octane rating is used in high performance petrol engines that have a higher compression ratios. The octane requirement of an engine varies depending on compression ratio, mechanical design, and environmental operating conditions
In the UK, standard unleaded now has a RON of 95, while super unleaded is around 98 RON. Some fuel companies also market a top-of-the-range fuel with a RON of 102.
What does Premium fuel do?
Higher-octane fuels help to prevent ‘knocking’ or ‘pinging’. This occurs when unburned fuel pre-ignites in a vehicle’s engine. The higher the RON of a fuel, the more likely it will be to burn in a controlled manner in the engine, thus lowering the chance of ‘knocking’. Prolonged ‘knocking’ could possibly lead to damaged interior engine components.
Are there any benefits?
The higher octane rating of super or premium unleaded petrol should make it burn more efficiently, thus in theory delivering better performance – more power for less fuel burned. In the real world however, it generally depend on a range of factors such as how you drive and what type of car you have.
Premium fuel can also include detergent additives that help to keep your engine clean, which should mean that it keeps working efficiently for longer.
Is it worth paying more?
A number of respected motoring organisations have reported that the possible benefits provided by premium fuel do not justify the additional cost. The simplest way to determine if premium fuel can help to reduce your fuel consumption is to fill-up with three separate tankfuls for example and monitor the distance travelled to see if you notice any difference when compared with regular fuel.
All vehicle manufacturers will recommend the most appropriate fuel rating to ensure optimum fuel economy and engine longevity.