What is the function of engine oil in a combustion engine?

Engine oil in a combustion engine has three main functions: It reduces wear on moving parts (wear protection), helps dissipate heat from components (cooling), and removes dirt and particles from inside the engine (cleaning). All three functions are essential for the proper operation and longevity of the engine, which is why all answers here are correct. Remembering these functions will help you recognize why regular oil maintenance is important for vehicle performance and durability.