变速箱油在起到润滑作用的同时，还会起到动力传导、齿轮散热、防腐防锈、清洁等功效，因此相比起发动机机油，变速箱油的流动性要更高，如果你见过实际的自动变速箱油便会发现，它的质地更加接近水，是一种很稀的液体，而非发动机机油那般粘稠。
Transmission oil not only plays a role of lubrication, but also has the functions of power transmission, gear heat dissipation, anti-corrosion and anti rust, cleaning, etc. Therefore, compared with engine oil, the mobility of transmission oil is higher. If you have seen the actual automatic transmission oil, you will find that its quality is closer to water. It is a very thin liquid, not as viscous as engine oil.
如果长期不换变速箱油，变速箱油液的酸碱值会发生变化，变速箱里的齿轮便会受到腐蚀。此外，长时间不换油，油液的粘度也会提升，这就导致油液不能在短时间内润滑整个齿轮机构，从而造成齿轮过热、离合器片异常磨损等问题出现。其最直接的感受就是换挡顿挫增大、换挡间隙变长、凉车起步无力、挡把震动等。
If the transmission oil is not changed for a long time, the pH value of the transmission oil will change, and the gears in the transmission will be corroded. In addition, if the oil is not changed for a long time, the viscosity of the oil will also increase, which leads to the oil can not lubricate the whole gear mechanism in a short time, resulting in overheating of the gear, abnormal wear of the clutch plate and other problems. The most direct feeling is the increase of gear shifting frustration, longer shifting clearance, weak starting when the car is cold, and the vibration of gear handle.