美国内燃机油新规格对粘度指数改进剂的挑战

过去20年低温泵送性是发动机油重要的指标，但是历来都只针对新油，最近才对使用后油的有所要求。受到各种因素的影响，在发动机整个使用过程中油品低温泵送性可能变得很差。本文使用工业发动机以及专用的发动机试验来考察使用后油品的低温泵送性，特别考察了粘度指数改进剂对其的影响。实验表明：使用某些种类的粘度指数改进剂其使用后油品可保持不错的低温泵送性能，而使用另一类粘度指数改进剂则使用后油品的低温泵送性变差，尽管他们的低温启动性并不受到多大影响，降凝剂也对用后油低温泵送性影响不大。

IMPACT TO VI IMPROVER BY API ENGINE OIL NEW SPECIFICATION

Low temperature pumpability has been an important requirement of engine oils for the past two decades. However, until recently this requirement has applied only to fresh oils. Low temperature pumpability can deteriorate significantly during oil's life cycle in the engine due to the influences from many factors.The effect of in-service aging on low temperature pumpability of oils is examined with a variety of industry and proprietary engine tests. In particular,the role of viscosity index improvers in this regards is investigated. The data show that the oils formulated with certain Viscosity Index Improvers tend to maintain robust low temperature pumpability.But another Viscosity Index Improvers tend to cause the deterioration of low temperature pumpability of the used oils despite there are not much influence of their low temperature startability, also pour point depressant can not make it survived.