High temperature impact

① Lubricating oil will oxidize and lose its effectiveness if exposed to high temperatures for a long time, resulting in blackening and thickening.

② The corrosion inside the lubricating oil increases, such as acidic substances formed during engine operation.

③ Increase of carbon deposits, oil sludge, paint film and other substances.

impurity

It mainly comes from dust in the air, metal abrasive particles, leakage substances (fuel, water, etc.), lubricating oil oxides, and substances produced by fuel combustion.

Additive failure

Some lubricants experience a decline in performance due to the depletion or failure of their additives. For instance, when the anti-wear agent in a lubricant is depleted, its anti-wear properties diminish.

Viscosity index improver failure

Because its organic molecule long chain is broken, it no longer has the effect of increasing viscosity.

Base oil failure

Base oil is the carrier of additives, and if the base oil fails, the additives will not work.

Although there are national standards to determine whether the engine lubricating oil should be replaced, most car owners or maintenance personnel mainly rely on the mileage/time (specified by the manufacturer) and the color and viscosity of the lubricating oil to judge when to change the oil. In fact, all of the above methods have some unreasonable points. For example, judging based on color, some brands of new lubricating oil appear black, and some lubricating oil may also turn black due to excessive addition of detergent dispersant, but at this time the lubricating oil has not failed, which may cause misjudgment for people with insufficient experience. A simpler and more effective way is to use filter paper or electronic instruments to judge whether the lubricating oil has failed.