1. lubrication: One of the primary functions of engine oil is to lubricate the moving parts within the engine. The various components, such as pistons, crankshaft, camshaft, and bearings, experience a lot of friction and heat during operation. Engine oil forms a thin film between these moving parts, reducing friction and preventing wear and tear.
2. Heat Dissipation: As the engine operates, it generates a significant amount of heat. The oil helps in dissipating this heat by carrying it away from the hot engine components. This prevents the engine from overheating, ensuring that it operates within the optimal temperature range.
3. Cleaning: Engine oil acts as a cleaning agent, picking up dirt, debris, and contaminants that may accumulate in the engine. The oil filter helps in trapping these impurities, preventing them from causing damage to the engine components. Regular oil changes are necessary to maintain the cleaning efficiency of the oil.
4. Sealing: Engine oil helps in forming a seal between the cylinder walls and the pistons, preventing combustion gases from leaking into the crankcase. This contributes to the efficiency of the engine and ensures that it runs smoothly.
5. Corrosion Protection: Oil also provides a protective layer on metal surfaces, preventing corrosion and rust. This is crucial for maintaining the longevity of the engine and its components.

In summary, engine oil plays a crucial role in ensuring the smooth operation, longevity, and efficiency of a car engine by providing lubrication, dissipating heat, cleaning, sealing, and offering corrosion protection to various engine components. Regular oil changes are essential to maintain the effectiveness of the oil in performing these functions.