Oil is either a petroleum or synthetic substance used to lubricate machinery, reduce friction, and protect surfaces from wear, contamination, and corrosion. It is available in a range of viscosities, a measure of thickness. The higher the viscosity, the more liquid-like and free flowing it is. Oil with a lower viscosity is thicker and better clings to components and parts. Oil is used in a wide range of industrial applications including metalworking, food processing, and pneumatics.