What is the primary function of engine oil in an internal combustion engine?

The primary function of engine oil in an internal combustion engine is to lubricate moving parts. Lubrication is essential for reducing friction between the various components of the engine, such as pistons, bearings, and camshafts. This reduction in friction helps to prevent wear and tear on these parts, which can lead to engine failure over time. The oil forms a protective film between the components, allowing them to move smoothly and efficiently.

While engine oil can contribute to other functions—such as cooling engine components, enhancing fuel efficiency, or indirectly supporting engine performance—its core role is primarily centered around lubrication. Proper lubrication ensures that the engine operates effectively and extends its lifespan by minimizing damage caused by metal-to-metal contact.