What is the primary function of engine oil in a vehicle?

• A. To clean the fuel system
• B. To lubricate engine parts, reduce friction, and help to cool the engine
• C. To act as a coolant
• D. To increase fuel efficiency

Answer: (B)

The primary function of engine oil is to lubricate engine parts, reduce friction, and help to cool the engine. Lubrication is vital in minimizing wear and tear on the engine components, as it forms a protective film between moving parts. This film reduces friction, which is crucial because excessive friction can lead to overheating and potential damage over time.

Additionally, engine oil plays a role in cooling by dissipating heat away from the engine components, especially during high operations. While engine oil can assist in cleaning by suspending dirt and residues within it, its main purpose revolves around lubrication and cooling, which directly contribute to the engine's efficiency and longevity.