Crude oil being poured into a beaker. Crude oil is oil from the ground before it has been refined. It contains a varied mixture of hydrocarbons, and the refining process at an oil refinery separates it into parts called fractions. As the crude oil is heated, the lighter hydrocarbon fractions boil off and leave the heavier fractions behind. Fractions that are obtained from crude oil include bitumen, fuel oil, lubricating oils, diesel, jet fuel, petrol, and petroleum gases. The fractions are used as heating, aircraft, and motor vehicle fuels, as industrial lubricants, and to make products such as plastics in the chemical industry. To compare the colour and viscosity of crude oil and its fractions, see T110/483-491 and T110/492-501.