After using the lubricating oil for a period of time, the color will turn black. Some car owners will think that the oil has seriously deteriorated and replace it, resulting in waste. Generally, the engine oil is added with detergent dispersant to wash the adhesive film and black carbon on the piston, so the color of the lubricating oil is easy to turn black after a period of use, but the oil at this time is not deteriorated. So why does the color of lubricating oil turn black? I'm here to tell you today.
First, the high content of olefin and sulfur in fuel (sludge is easy to form in gasoline engine and smoke is easy to form in diesel engine), which is easy to make the engine oil blacken and accelerate, so the fuel quality is the source of engine oil blackening.
Second, the structure and working conditions of the engine are different. For example, when the engine starts and stops, it is easy for the gasoline engine to generate sludge, and the diesel engine will not completely burn to form smoke stains, so it will turn black.
Third, in order to overcome the above results caused by fuel and machinery, dispersant should be added to the lubricating oil to prevent oil sludge or smoke stains from forming paint film on the cylinder or deposition in the body. The higher the quality of the oil, the better the dispersion, but the oil is prone to blackening, so high-quality oil is faster than low-quality oil.
Fourth, the oil blackening and sludge generation are also related to the long-term overload and high-temperature operation of the engine, the failure to clean the engine and oil bottom when changing the oil, and the filterability of the oil filter.
Warm tip: the oil change period of engine lubricating oil should be appropriate, too early will cause the waste of lubricating oil, too late will increase engine wear, shorten engine maintenance cycle and service life.