There are many reasons why the oil indicator light on the car dashboard lights up, mainly including the following points: 1. The oil viscosity is too high, the oil volume is insufficient, the oil bypass valve is faulty, etc. Oil viscosity has an important impact on oil quality. The higher the viscosity, the stronger the oil's resistance to high temperatures, and vice versa. However, the higher the viscosity, the better. We should choose the oil number that suits our engine. When the amount of oil is insufficient, the amount of oil pumped by the oil pump is reduced or air enters and the oil cannot be absorbed, resulting in reduced oil pressure and poor lubrication, which can easily lead to wear of the crankshaft, bearings, cylinder liners and pistons. When the oil bypass valve fails, due to softening of the pressure regulating spring or improper adjustment, the mating surface of the valve seat and the steel ball will be worn or stuck and cannot be closed, resulting in abnormal hydraulic pressure in the main oil circuit. 2. The engine temperature is too high. Long-term vigorous operation will put the engine in a high-temperature and high-load state. Although the oil volume is sufficient, excessive temperature will cause the oil to become thinner and flow out from the fitting gap, causing the hydraulic pressure to drop. 3. The oil pump is damaged. If the oil pump is damaged or there are too many gaps during the assembly process, and when the oil pump operates abnormally, the oil pump will not be able to pump oil normally, or it will not be able to pump out enough oil, resulting in insufficient oil pressure. 4. Improper oil selection. If the car owner is greedy for cheap and chooses oil with a low label or a viscosity that does not match the factory oil, it will also lead to poor lubrication, insufficient oil pressure, and an alarm. 5. The fitting clearance between the crankshaft and the large and small tiles is inappropriate. If the car owner who has overhauled the engine does not pay attention to the quality of the engine assembly, it may be too tight or too loose, causing the oil pressure to rise or fall.