The lubricating oil of the vehicle will turn black after a period of time. Some owners think that the oil has gone bad, and then replace it, resulting in unnecessary waste. In fact, the reason for turning black is not only because of deterioration, but also the following common situations:
Case 1: the structure and working conditions of the engine are different. For example, when the engine starts and stops, it is easy to generate oil sludge in the gasoline engine, and the diesel engine will not completely burn to form smoke stains, so it will turn black.
Case 2: high olefin and sulfur content in the fuel (sludge is easy to form in the gasoline engine and smoke stain is easy to form in the diesel engine), which is easy to make the engine oil blacken quickly, so the fuel quality is the source of engine oil blackening.
Case 3: 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 the oil bottom when changing the engine oil, and the filterability of the oil filter.
Situation 4: 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 easy to turn black, so the high-quality oil turns black faster than the low-quality oil.