The main reasons for the failure of the lubricating oil are as follows:

(1) the influence of high temperature

(1) lube oil is in a high temperature environment for a long time, and it will fail to oxidize and become black and thickened.

2. Corrosive substances in lubricating oil increase, such as acidic substances formed during engine operation.

(3) the increase of carbon accumulation, oil sludge and paint film.

(2) impurities

It is mainly derived from dust in the air, metal abrasives, leaks (fuel, water, etc.), lubricating oil oxides and substances produced by fuel combustion.

(3) failure of additive

Some lubricants fail because their additives fail or run out. For example, the use of antiwear agents in lubricating oil will reduce the wear resistance.

(4) failure of viscosity index promoter

Because of its long chain breakage of organic molecules, it is no longer sticky.

(5) failure of basic oil

The base oil is the carrier of additives, and the additive will not play a role in the failure of base oil.

Judgment method of failure of 2. lubricating oil

For the automobile industry, although there are national standards to determine whether the lubricating oil of the engine is replaced, most of the personnel change the oil mainly according to the mileage / time of the car (factory regulations) and the color and viscosity of the lubricating oil. In fact, the above methods are unreasonable. For example, judging by color, some brand new lubricants appear black, some lubricating oil adding clear dispersant too much also may turn black, and at this time the lubricating oil is not invalid, the less experienced person may cause misjudgement. A simpler and more effective way is to judge whether lubricating oil is invalid by means of filter paper or electronic apparatus.