What is the correct description of the three main purposes of oil?

• A. Lubrication, Cooling, Cleaning
• B. Lubrication, Cleaning, Sealing
• C. Cooling, Cleaning, Damping
• D. Lubrication, Cleaning, Heating

Answer: (A)

Oil has three main roles in mechanical systems: lubrication, cooling, and cleaning. Lubrication creates a protective film between moving parts, greatly reducing friction and wear and helping parts run smoothly. Cooling happens as oil absorbs heat from hot components and carries it to an oil cooler or radiator, preventing overheating. Cleaning occurs because circulating oil picks up dirt, metal particles, and combustion byproducts; detergents in the oil help keep these contaminants suspended so filters can remove them and surfaces stay cleaner. While oil can influence sealing to some extent, that isn’t its primary purpose, and heating is not a function of oil—its job is to remove heat, not to add it.