Blindly choose lubricating oil: Lubricating oil plays the role of lubrication, cooling, cleaning and sealing. The quality of lubricating oil is directly related to the service life of the engine. The blackening of engine oil is the deterioration of engine oil: engine oil works under severe high temperature conditions, which is prone to oxidation and deterioration, producing acidic substances and superimposing them into polymer deposits, thus destroying lubrication. Diesel vehicles use gasoline engine oil: engine oil is divided into gasoline engine oil and diesel engine oil. Although gasoline engines and diesel engines work under the same conditions of high temperature, high pressure, high speed and high load, there are still big differences between the two.