What is the primary purpose of engine oil?

The primary purpose of engine oil is to lubricate moving parts and reduce friction. In an internal combustion engine, various components such as the pistons, crankshaft, and camshaft are in constant motion. Without proper lubrication, these metal parts would grind against each other, leading to increased wear, overheating, and potential engine failure. Engine oil forms a protective film between these parts, allowing them to move smoothly and efficiently while minimizing direct contact.

While enhancing fuel efficiency, cooling the engine, and filtering contaminants are important functions associated with engine oil, they are secondary to its primary role of lubrication. The oil does help in improving fuel efficiency by reducing friction, and while it does assist in cooling by carrying heat away from engine components, cooling is not its exclusive purpose. Additionally, engine oil contains additives that help capture and hold contaminants, but the filtration of these contaminants is part of a broader maintenance goal rather than the central function of the oil itself.