润滑油常用知识（General knowledge of lubricating oil）.doc

润滑油常用知识（General knowledge of lubricating oil） General knowledge of lubricating oil The choice of gasoline engine oil 1. Quality grade: with engine compression ratio and additional device. The compression ratio between 7.5 and 8.5 is equipped with EGR (exhaust gas circulator), and the compression ratio is greater than 8.5 and the catalytic converter is installed. 2. Viscosity index: according to ambient temperature. Diesel engine oil selection 1. Quality grade: the strength of the engine can be used. The strengthening coefficient is 50-80. The CD is greater than 80, CF - 4. 2. Viscosity index: according to ambient temperature. Three, the oil viscosity bigger the better the argument is? Why is that? This statement is incorrect, because the oil viscosity is too large, there will be the following disadvantages: 1, engine starting difficulty to viscosity is too big, oiling too slow (oil pressure is high, but the oil throughput is not high) - starting difficulty - a brief of the dry friction or half liquid friction caused by engine wear abrasion is derived from the engine start (70%). 2, to reduce the power to viscosity is too large, parts wear and tear on the surface of the friction will increase, not only increase the wear parts, and after burning heat, will be more friction part into work, and to overcome the friction increases the reduced the effective power of engine, increasing the engine fuel consumption. 3. The cooling effect is poor, the viscosity is too large, the speed of the lubricating oil is slow, and the heat loss is reduced. 4, poor washing effect to viscosity is too large, the cycle of lubricating oil slow - through the filter of less - not will clear in time the scrap metal, carbon particles, dust, etc from the friction surface washing out. 4. If the viscosity is too small, the following disadvantages will be also: 1. The oil film is easy to be damaged. The viscosity is too small to form enough oil film. 2. The sealing function is not good. It is easy to