Oil products. Test tubes of various products obtained from crude oil. Crude oil is a mixture of hydrocarbons that is heated to separate (refine) it into parts called fractions. The hydrocarbons vary in size and the lighter fractions boil off first. These fractions are arranged here in order of boiling point from left to right (highest to lowest): bitumen, fuel oil, heavy, medium, light lubricating oils, diesel, jet fuel (kerosene), and petrol (gasoline). The colours and viscosity also vary from left (dark and viscous) to right (clear liquid). Oil products are used as aircraft, motor vehicle and heating fuels, 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.