The myth of 95
It is believed that 95 octane fuel will dramatically increase your vehicle’s performance in comparison to using 93 octane, this is false according to Adrian Velaers, Senior Technical Advisor – Retail and Commercial Fuels Sasol Energy.
Dependent on engine design, some petrol engines will ignite the fuel in an uncontrolled manner, this is known as a “knock”. The Octane indicates a fuel’s resistance to this knock phenomenon, 95 octane is more resistant than the alternative 93 octane.
Most consumer vehicles will lack the knock during the combustion cycle and will perform perfectly using 93 octane inland and 95 octane at the coast. Purpose built performance engines and engines fitted with a turbocharger are more susceptible to knock with the increased air pressure and will most likely need the higher octane petrol to run more efficiently.
In the event you fill up with an octane against the manufacturer’s recommendation for your particular vehicle, your engine control unit (ECU) will automatically adjust its spark timing to compensate for the difference in octane. Jakkie Olivier, CEO of the Retail Motor Industry Organisation (RMI) still recommends using the octane recommended by the manufacturer as indicated in the owner’s manual or inside the flap covering the petrol filler cap to avoid losing your warranty.
