Why does the Passat's oil warning light keep coming on when there's no lack of oil?

[VonJoanna]

Passat's oil warning light keeps coming on when there's no lack of oil for the following reasons: Excessive oil viscosity: The viscosity of the oil is closely related to its quality. The higher the viscosity, the better the oil's resistance to high temperatures, and vice versa. However, higher viscosity doesn't always mean better. Car owners should use oil grades that match their engine specifications. Pressure relief valve clogged or improperly adjusted: To prevent excessively high oil pressure in the lubrication system, which increases engine power consumption and causes oil leaks at sealed connections in the oil circuit, a pressure relief valve is installed in the main oil passage or oil pump. Its function is to limit the oil pressure in the lubrication system to ensure it doesn't exceed the specified value. A faulty pressure relief valve can lead to abnormal oil pressure, causing the oil warning light to illuminate.