The octane number indicates your car fuel's anti-knock rating and is a measure of the fuel's ability to resist engine knocking. Knock occurs when the fuel-air mix in the cylinder explodes instead of burning in a controlled way. If fuel has a high octane number, it will have a higher resistance to engine knocking. This is determined according to RON (Research Octane Number) under specific test conditions using precisely defined test engines. Regular Unleaded has the lowest rating at 95 RON, followed by Super Unleaded with 98 RON. The higher the octane number, the higher the self-ignition temperature of petrol and the lower the knock tendency during combustion (self-ignition temperature of regular fuel 450-550 °C, Super fuel 480-700 °C).