The part of the lower part of the cylinder block for mounting the crankshaft is called the crankcase, and the crankcase is divided into the crankcase and the lower crankcase. The upper crankcase is integrally formed with the cylinder block, and the lower crankcase is used for storing lubricating oil and closing the upper crankcase, so it is also called an oil sump diagram. The oil sump is very stressed and is usually stamped from thin steel sheets, the shape of which depends on the overall arrangement of the engine and the capacity of the oil. The oil sump is equipped with a stabilizing oil baffle to prevent the oil surface from fluctuating excessively when the car is turned. The bottom of the oil pan is also equipped with an oil drain screw. Usually, the oil plug is equipped with a permanent magnet to absorb the metal chips in the lubricating oil and reduce the wear of the engine. A gasket is placed between the upper and lower crankcase joint surfaces to prevent oil leakage.