Red Seal Automotive Service Technician Practice Exam

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

1. To fuel the engine

2. To lubricate, cool, clean, and seal moving parts

3. To enhance engine performance only

4. To reduce engine weight

The correct answer is: To lubricate, cool, clean, and seal moving parts

The main function of engine oil is to lubricate, cool, clean, and seal moving parts within the engine. Lubrication is critical as it reduces friction between the engine components, which helps prevent wear and tear over time. This is essential for maintaining the longevity of the engine. Additionally, engine oil plays a significant role in cooling by dissipating heat generated during combustion and the operation of engine parts. Cleaning is another crucial function, as engine oil serves to carry away dirt, metal particles, and other contaminants that accumulate over time. It keeps the engine clean by suspending these particles and allowing them to be trapped by the oil filter. Furthermore, engine oil helps to seal the gaps between moving parts, such as piston rings, which enhances efficiency by preventing combustion gases from escaping. In contrast, the other options do not encompass the primary purposes of engine oil. While fuel is required for the engine to operate, engine oil is not a fuel and does not provide energy. Enhancing engine performance is a benefit of effective lubrication and maintenance but is not the sole or main function of engine oil. Lastly, reducing engine weight is not achieved by the engine oil itself but rather by the materials used in engine construction. Thus, the primary role of engine oil