Red Seal Automotive Service Technician Practice Exam

What does engine oil provide in addition to lubrication?

1. Increased fuel consumption

2. Coolant properties

3. A seal between piston rings and cylinder walls

4. A barrier to dirt

The correct answer is: A seal between piston rings and cylinder walls

Engine oil plays a crucial role in maintaining the overall health and efficiency of an engine. In addition to providing lubrication to reduce friction among various moving parts, it also acts to create a seal between the piston rings and the cylinder walls. This sealing action is vital because it helps maintain the proper compression in the combustion chamber, which is essential for optimum engine performance. A good seal ensures that the combustion gases do not leak past the piston rings, thereby improving efficiency and power output. The ability of engine oil to form a seal is attributed to its viscosity and the presence of additives that enhance this property. By ensuring a tight seal, the engine oil helps maintain the necessary pressure in the combustion chamber for the ignition process, thus enhancing engine performance. On the other hand, options like increased fuel consumption and coolant properties do not accurately reflect the functions of engine oil. Increased fuel consumption would be a negative effect, which is not typically a goal of engine oil use. While some engine oils may have minor cooling effects by absorbing heat, they are not primary coolants; that role is better suited to the coolant system. Lastly, while engine oil may help repel some dirt and contaminants, its sealing function is much more critical in engine operation. Thus, the sealing property underscores the