engine oil

Engine oil is a lubricant derived from crude oil after fuels have been removed. Its primary function is to reduce friction between moving engine parts by creating a film. The oil's viscosity, or resistance to flow, is crucial and is classified by numbers, with lower numbers indicating lighter oil. This viscosity must match the engine's cooling requirements, as oil also helps dissipate heat.

Additives are used to improve oil performance by reducing oxidation, preventing corrosion, and acting as detergents to keep the engine clean. Multigrade oils, like SAE 10W40, are designed to maintain proper viscosity across a range of temperatures, ensuring effective lubrication in both cold starts and high-temperature operation. Regular servicing of oil filters is important for removing contaminants, though chemical reactions can still degrade the oil over time.