The general price of oil-water separator is around 400 yuan: 1. Oil-water separator is mainly based on the density difference between water and fuel oil, which uses the principle of gravity settlement to remove impurities and moisture, and has separation elements such as diffusion cone and filter screen inside. 2. The oil-water separator has other functions, such as preheating fuel to prevent wax deposition and filtering impurities. 3. The oil-water separator is a kind of fuel filter, and its main function is to remove water from diesel oil, thus reducing the faults of fuel injectors and prolonging the service life of engines; 4. Oil-water separator can only separate the water in fuel and engine oil, which has a certain effect on improving engine oil consumption.