The cost of filling the family car has grown in recent weeks, fuel prices once again trending upwards. Following the Government halving of fuel excise the price at the bowser dropped below the $2.00 mark however it is now well over that figure. Which prompted me to reflect on some myths regarding premium petrol.

There’s an argument out there that the use of dearer 98 RON premium fuel will provide more performance and better economy. But for motorists driving cars designed to run on regular unleaded paying the extra for premium fuel is often a waste of money because the car can’t take advantage of the dearer fuel’s properties.

With low compression engines like V8’s and older models there is no tangible benefit in using premium fuel whereas in most modern high compression turbocharged engines with direct injection it offers much. Check the recommended fuel grade on the inside of your filler cap.

Octane rating is a scale that defines a fuels tolerance for compression – the difference between 95 RON and 98 RON for example is knock resistance – 98 RON more stable and resistant to knocking. But putting 98 RON in say a 1990 Toyota Corolla designed to run on 91 RON is simply wasting your money.

Most modern turbo engines today are programmed to run on 98 RON premium for best results but in some cases you could try 95 RON and save money.

I’m David Berthon.

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