Purpose of the engine lubrication system (Mercedes-Benz Sprinter 903)

The main purpose of the engine lubrication system is to reduce wear on the engine's rubbing parts: pistons, cylinders, crankshaft bearings, and valve timing mechanism. Motor oil also performs a sealing function - it seals the gap between the piston and the cylinder walls, where, despite special rings, there is a gap of thousandths of a millimeter. In addition, the oil also performs a cooling function. When fuel is burned, only a third of the energy obtained is used to perform useful action. The remaining part leaves the engine as heat along with the exhaust gases. Another portion of the thermal energy is removed through the cooling system and oil. For example, on the one hand, heat from the piston is removed through the rings and the oil layer and then through the cylinder walls by the coolant. On the other hand, the piston is directly cooled by the oil sprayed into the crankcase. In addition, all bearings of the crankshaft and camshaft, etc. are cooled by oil. Then the heat absorbed by the oil is released into the atmosphere through the oil pan.

When designing engines, other additional requirements are imposed on the oil: for example, it should not evaporate at high temperatures occurring on the working surface of the cylinders, and the oil film should not be damaged under these difficult conditions. Oil combustion should not be accompanied by the formation of carbon deposits, since oil consumption is caused by the combustion of part of it during engine operation. The oil should also wash away soot and dirt so that they do not accumulate in the engine. It should not lose its properties over time and should also prevent contamination of the engine, etc.

(Material based on data from the portal: mercedesman)