Petrol is a product derived from petroleum through a process called fractional distillation. Petroleum includes crude oil and many other fuels and needs to be separated through what is known as a fractionating column. Petroleum is found when drilling for oil and is then taken and distilled into many fuels such as petrol, kerosene to chemicals used to make plastic. It is estimated that we use around 95 million barrels of oil a day worldwide.

Engines that use petrol work in a different way to diesel engines. Petrol engines are spark ignition internal combustion engines, meaning that the fuel is ignited through a spark from a spark plug. If the ignition happens early or is mistimed then a metallic pinging noise is heard, known as knocking. This can damage the engine badly, and if you notice it let your garage know so they can advise on the next step.

The petrol that we see on the forecourts is a product of petroleum and is a different fuel to diesel, even though it is made from the same base product. Petrol types are measured in octane numbers and ratings depending on the resistance to autoignition.