The most commonly sold fuels are the unleaded varieties: unleaded (ULP), premium unleaded (PULP) and ultra premium unleaded (UPULP).
Unleaded fuels carry a RON (Research Octane Number) rating. Put simply, RON determines petrol’s ‘anti-knock’ quality or resistance to pre-ignition. If you run your vehicle on low octane petrol you might notice a ‘knocking’, ‘rattling’ or ‘pinging’ sound which means the fuel is detonating instead of burning smoothly. This is not only a waste of energy; it may also damage your engine in the long run. Fuel with a higher octane number suitable for your vehicle’s engine will eliminate knocking.
But NRMA Motoring & Services’ Jack Haley says it’s a widespread but misguided belief that if you use a high octane fuel your car’s performance will automatically increase.
“You won’t achieve any improved performance from using higher octane fuels unless your vehicle’s engine is designed for them,” he says.
If you are in any doubt, check your owners manual to find out what type of fuel your engine is designed for or call Tech Advice on 1300 655 443.
ULP is classified as 91 RON. Locally produced vehicles, plus most Japanese cars, are designed to run on it and these don’t generally benefit from premium or ultra premium petrol. Some pre-1986 cars, like the KC Laser and Mazda 323, can also use ULP.
Premium brands carry a 95 or 96 RON rating. Most European cars are designed for PULP because it is the standard octane there.
A few vehicles such as Subaru’s WRX STi, some Porsches and high-powered Mercedes and BMWs are optimised for 98 RON or UPULP. These cars can run on lower octane fuels but they will drop a small amount of power.
Some pre-1986 vehicles, such as Kingswoods and early Falcons, need an octane rating of 97 or more to run normally. LRP, once offered as a leaded petrol substitute, was a blend of premium unleaded petrol and valve protection additives.
“As LRP is no longer available at the pump, motorists have to buy the additive themselves and mix it with PULP according to the recommended concentration,” says Jack.
LPG is made from butane and propane and is cheaper than petrol. If you like the idea of LPG, you have two options.
“You can go for a factory fitted model, such as the Ford Falcon, which is a dedicated LPG model,” says Jack. “Or you can go for a ‘bi-fuel’ version. These retain their petrol systems, with the LPG usually added by an approved installer after the car is sold.
“The cost of modifying your existing vehicle can be high. You should also check with the manufacturer that your vehicle’s engine is suitable for LPG.”
Mainly used for fleet cars, heavy vehicles, some 4WD and commercial vehicles. New Commonwealth Fuel Quality Standards require diesel to have lower sulphur levels necessitating a more intensive refining process.
Shell has just released a 100 RON premium fuel with 5 per cent ethanol (an alcohol fuel alternative that can be produced from crops). NRMA supports a 10 per cent blend of ethanol to petrol as long as it doesn’t increase costs for motorists. It should not be used in some older vehicles (check with your manufacturer), and the excise is subsidised until 2011.
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