Why lubricating oil must have excellent thermal oxidation stability?
1. Because the engine in the high temperature lubricating oil itself hydrocarbons with air and NO1, NO2 and SO2 oxidation reaction generated alcohol, aldehyde, ketone, acid oxygen containing compounds.
2 high temperature, engine cooling is not good, is volatile oil, increase the consumption of lubricating oil.
3, cylinder piston working conditions, under the high temperature surface oil film by the reciprocating motion, uneven high mechanical load and stroke outbreaks in high shear rate of the lateral pressure on the surface stress is very big, the oil film is destroyed and oxidation.
4, lubricating oil under the condition of high temperature oxidation process was fierce, thin layer of oil on the surface of the parts, the part of light fraction were evaporated, another part of the depth under the metal catalytic oxidation, finally generated pinch off, the surface film is deposited on parts.
5, while the lower crankcase medium oil temperature, but due to the agitation and splash lubrication is strong, and contact area is large, oxygen oxidation is fierce, oil soluble and insoluble content increasing.
6, sedimentary carbides in the piston groove and adsorption gas, coking, further formation of paint film, film has great harm, make the cylinder wear.
7, especially modern high-performance engine, thermal load is very high, if some supercharged diesel engine to the piston inner cavity injection to reduce the temperature of lubricating oil, it puts forward higher requirements on lube oil oxidation stability. To sum up, the engine lubricating oil must have excellent thermal oxidation stability.
