What is the primary function of engine oil?

The primary function of engine oil is to lubricate moving parts and reduce friction. Lubrication is essential in an engine because it minimizes wear between components that are in constant motion, such as pistons, crankshafts, and camshafts. By reducing friction, engine oil helps to ensure smooth operation, enhances performance, and extends the lifespan of the engine parts. Additionally, proper lubrication helps control engine temperature by reducing heat generation caused by friction and facilitates the removal of contaminants and debris through oil circulation, which can accumulate in the engine over time.

While other choices mention aspects related to engine performance or maintenance, they do not capture the core purpose of engine oil, which is critical for the engine's operational integrity and longevity.