What is the primary purpose of engine oil in a four-stroke engine?

The primary purpose of engine oil in a four-stroke engine is to lubricate moving parts and reduce friction. Engine oil creates a thin film between surfaces that are in contact with each other, such as bearings, crankshafts, and camshafts. This lubrication minimizes wear and tear on these components, allowing them to operate smoothly and efficiently.

By reducing friction, engine oil helps to lower the temperatures produced during operation, which can prevent overheating and prolong the life of the engine. In addition, proper lubrication contributes to the overall performance of the engine by ensuring that it runs quietly and efficiently, minimizing energy loss.

While improving fuel efficiency, increasing engine speed, and enhancing horsepower are benefits that can arise from effective lubrication, they are not the primary functions of engine oil. The focus of engine oil is fundamentally on providing lubrication and protection for the engine's internal components.