1. Causes of lubricating oil failure
(1) High temperature effect
① lubricating oil has long been in high temperature environment, it will oxidize and become black and thicken.
② the internal corrosion of lubricating oil, such as the formation of the engine work of acidic substances.
③ accumulation of carbon, sludge, paint film and other substances increased.
Mainly from the air dust, metal abrasive, leakage (fuel, water, etc.), lubricating oil oxides and fuel burning substances.
(3) Additive invalidation
Some lubricants are degraded because of the expiration or use of additives. For example, the antiwear agent used in lubricating oil will reduce the abrasion resistance.
(4) Failure of viscosity index modifier
Because its organic molecule long chain breaks, no longer have the viscosity-increasing effect.
(5) Failure of base oil
Base oil is the carrier of additive, and the additive does not play a role in the failure of base oil.
2. Oil failure Judgment method
Although there is a national standard to determine whether the engine oil replacement, but most of the owner or maintenance staff to change the oil is based on the car mileage/time (manufacturer regulation) and lubricants color and viscosity to judge. In fact, there are some unreasonable methods. For example, according to the color of the judgment, some brands of new lubricants will appear black, some lubricants into the detergent too much also may become black, while the lubricant is not expired, the inexperienced people may cause misjudgment. The simpler and more effective way is to use the filter paper or electronic instrument to determine whether the lubricating oil is ineffective.