The load operation of gearbox will destroy the quality and friction characteristics of gearbox oil, increase friction and wear, and the noise of gearbox will follow. At the same time, sludge (impurities or dirt) will also be produced inside the gearbox (such as the valve body), which will lead to the gearbox's frustration, gear shifting, impact, slipping, abnormal sound, hysteresis, high temperature and oil leakage. (Audi and other high-end models will call the police and enter the gearbox protection mode. If it is not solved in time, the gearbox will be scrapped.

Therefore, only by removing stubborn dirt and impurities in the gearbox and effectively controlling the working temperature of the gearbox can the gearbox problem be completely solved and prevented from happening again.