Lubrication oil deterioration, worse, may lead to abnormal wear of engine, shorten the service life of the engine. There are many causes of oil deterioration:
一、空气滤芯破损。空气滤芯的作用是过滤进入发动机内部的空气中的杂质，达到净化空气的作用。空气滤芯有着一定的使用寿命，寿命长短与环境和材质相关。灰尘多和潮湿的地方容易缩短空气滤芯的使用寿命，由于空气滤芯大多数是由纸质压缩而成，潮湿的环境会使得空气滤芯寿命缩短。当空气滤芯失去过滤效果或破损之后，空气中的杂质非常容易进入发动机舱内部，细小的灰尘更加容易进入到机油当中。灰尘还可以通过气缸进入曲轴箱导致机油的油泥和粘度增加，使机油润滑性变差，甚至堵塞机油，导致发动机异常磨损。
A damaged, air filter. The air filter's role is to filter into the impurities inside the engine in the air, can achieve the function of purifying air. The air filter has certain service life, the length of life and the environment and related materials. Dust and damp places easy to shorten the service life of the air filter, air filter is because most by paper made of compressed, humid environment will make the air filter to shorten life. When the air filter filter effect of lost or damaged, the impurity in the air very easy access to the engine compartment inside, fine dust more easily into the oil. Dust can also enter the crankcase through the cylinder causes the oil sludge and viscosity increase, so that the oil lubricating property become worse or even blocked oil, lead to abnormal wear of engine.
二、机油遇水稀释、乳化。气缸垫损坏或其他原因使缸体或曲轴箱进水，当含水量超过0.1%时，机油添加的抗氧化剂、清净分散剂等就会失效，因而加速机油的氧化过程。机油中含较多的水时，机油润滑性变差，粘度下降，机油油膜抗摩擦效果差，轻则导致机油过早变质和机件生锈，重则引起发动机抱轴、烧瓦等严重机械事故。
Two, oil water dilution, emulsification. Damaged cylinder head gaskets or other reasons to make the cylinder or the crankcase water, when the water content is more than 0.1%, oil added antioxidant, dispersant and so on will fail, and thus accelerate the oxidation process of oil. Containing more oil in water, oil lubrication variation, decrease viscosity, oil film anti friction effect is poor, light to cause oil premature deterioration and parts of rust, weight is caused by engine axle, the tile burning and other serious mechanical accident.
三、燃烧室密封不严。如果活塞环或气缸磨损后未及时发现，导致燃油长期窜入曲轴箱与机油接触，长期的高温致使机油变质、粘度下降、行成油膜的效果差等等。如此一来，油膜对活塞环与汽缸壁的润滑和密封效果渐渐失效，活塞环与汽缸壁的摩擦不断加大。长期如此，每当活塞做工一次，高温火焰进入曲轴箱的次数增加，恶性循环不断，导致曲轴箱内机油润滑失效，最终导致烧瓦等问题出现。
Three, the combustion chamber is not tightly sealed. If the piston ring cylinder after wear or not in time, lead to fuel long-term into the crankcase and oil contact, long-term high temperature cause the oil deterioration, decrease viscosity, for oil film effect difference and so on. Thus, the lubricating oil film on piston ring and cylinder wall and the sealing effect fades, the friction of piston ring and cylinder wall increasing. So long, when the piston work time, high temperature flame into the number of the crankcase is increased, leading to a vicious circle continue, crankcase oil lubrication failure, ultimately causing the problem of burning tile etc..