Does the gearbox need oil? Why can't you add oil?

In car maintenance, the gearbox is an indispensable part, responsible for transmitting the power of the engine to the driving wheels of the car. However, some car enthusiasts often wonder: why can't oil be added to the gearbox? Let's answer this question in detail below.
Firstly, to ensure the normal operation of the gearbox, we should have some basic knowledge. A gearbox achieves the conversion of different vehicle speeds through a series of gears. Unlike the engine, the gearbox does not require cooling like the engine, so there is no dedicated cooling system inside the gearbox. Therefore, the gearbox does not require the addition of oil for cooling purposes.
Secondly, the lubrication of the gearbox requires the use of special gear oil instead of engine oil. Gear oil has higher viscosity and can provide better lubrication under high temperature and high pressure conditions. Gear oil usually has higher viscosity and better shear resistance, which can better protect the gears and bearings inside the gearbox compared to engine oil.
In addition, the gears and bearings inside the gearbox are carefully designed and manufactured using special materials. Therefore, the components inside the gearbox do not require additives in the oil, which may have a negative impact on the materials inside the gearbox. If oil is added incorrectly, it may cause damage to the internal components of the gearbox, thereby affecting the normal operation of the gearbox.
In summary, gearboxes do not require the addition of engine oil because they do not require cooling and require the use of special gear oil to provide appropriate lubrication. Mistakenly adding oil may cause damage to the internal parts of the gearbox, so this error should be avoided. When carrying out gearbox maintenance, we should choose appropriate gear oil and regularly replace and maintain it according to the manufacturer's recommendations.