At a time when petrol prices are relatively unpredictable, except that they seem to go up as long as the Middle East conflict continues, motorists are considering switching to 93 octane petrol for marginal savings.
While the price difference is almost negligible – currently around 11 cents per litre inland – switching to the cheaper grade may represent noticeable savings in the long run.
Before making the switch, motorists need to understand why there are two different grades of unleaded petrol in South Africa, what sets them apart, and how their purposes differ.
According to Sasol, their consumer feedback shows that many motorists are using 95 octane petrol “without any benefit”, resulting in what it calls “octane wastage”.
“The octane rating of petrol refers to the fuel’s tendency to ‘autoignite’ and a higher number indicates a slightly reduced autoignition tendency,” explains Sasol.
Simply put, a fuel’s octane rating represents its ability to resist auto- or pre-ignition, which can cause pressure spikes that damage components over time.
Thus, higher-octane fuels burn in a more controlled manner under high compression, making them better for high-performance vehicles.
Sasol advises motorists to consult their car’s owner’s manual or the label inside the fuel flap to see which grade the manufacturer recommends for the model.
“Many cars are fully compatible with lower octane fuel, even as low as 91, and these cars will run safely and efficiently on 93,” notes Sasol.
It adds that 93-octane unleaded petrol in South Africa is similar to the fuel grades in international markets.
“In real terms, the difference between an octane rating of 93 and 95 is relatively small and, contrary to popular belief, the octane number does not refer to the energy content of the fuel,” it says.
Their colour differences come down to dyes, which are added after production, to make identification easier.
“Both fuels look exactly the same after production, but 95 is dyed green, and 93 is dyed yellow for identification purposes in the logistics system,” notes Sasol.
Choosing the right grade for your car
Should you follow your car manufacturer’s recommendations to a tee, and your petrol considerations are based on more than merely the minor savings, you will need to choose a grade and stick with it.
According to Auto Pedigree, your car’s compression ratio determines what octane fuel you should fill it up with.
“Engines with high compression ratios have more horsepower and require a higher octane fuel,” the retailer explains.
“The more stable, higher octane fuel reduces the risk of igniting, allowing better performance and efficiency.”
It adds that, simply, high-performance cars require higher octane fuels, while the average road vehicle will run well on 93 octane.
“It’s highly unlikely that an average car will see any performance gain by using 95 octane,” notes the retailer.
The Automobile Association of South Africa (AA) also recommends that, unless your car is turbocharged, you should choose 93 octane unleaded petrol.
“Having said that, there may be exceptions that are influenced by various factors such as altitude, driving and environmental conditions,” Auto Pedigree adds.
“If in doubt, consult your vehicle owner’s manual to ensure you’re filling up with the optimal type of fuel for your particular car. Who knows, you might find yourself saving a few needed rands.”
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