Tue Dec 11 18:10:49 CST 2018
Release person : 784 Release time : 2018-02-01
After a period of time, the engine oil can not be used any more, and the new oil must be replaced. The physical and chemical properties of the used engine oil have been changed by the foreign substances in the oil and the oil itself, resulting in harmful substances. We should combine the engine condition and the oil trend, considering whether to change the oil.
First, the viscosity
Oil viscosity is too high, low temperature start-up and pumping performance deterioration, the cooling effect of the decline, the engine friction, wear and have a negative impact. Viscosity is too low, oil lubrication capacity decline, will increase the wear and tear. Therefore, the viscosity of most of the provisions of the scrapping index 100 ℃ kinematic viscosity range does not exceed 20% -25%, there are provisions not exceeding the SAE viscosity of the oil level. Probably due to the degree of diesel engine enhancement in recent years and the increasing performance of oil cleaning and dispersing, the upper limit of variation of viscosity of diesel oil is allowed to 35%.
Second, insoluble matter
From n-pentane and benzene insoluble matter can generally determine the oil pollution. The limit of the content of oil insoluble matter is quite different.
Due to the wide operating temperature range of automotive engines, it is unavoidable to enter a small amount of condensate in the oil, which may be a sign of coolant pump leakage. Therefore, the maximum value of oil has been generally used to locate 0.5% of water, more than this value indicates that there may be free water.
Fourth, the sum value
The engine is most susceptible to acid corrosion of the parts are bearings. Tin or lead-based bus alloys better corrosion resistance, diesel bearings are mostly susceptible to corrosion of copper - lead alloy, the original diesel oil acid value of the scrapped standard set at 0.5.After using additive oil, due to some metal salts Additives and potassium hydroxide chemical reaction, the new oleic acid value is sometimes far exceeded the provisions of 0.5. Therefore, the acid value of the used oil should be based on the oil additives and acid value changes to provide the maximum limit. Or only stipulates the minimum depreciation of used oil without controlling the acid value.
Fifth, the flash point and fuel dilution
These two indicators are interrelated and all significantly affect the viscosity of the oil. Therefore, it is advisable to consider the viscosity together as a scrap index.