The automatic transmission oil needs to be replaced after a certain period of use, but the transmission oil is very high, and it is easy to have various problems if it is not changed well. Some people say, "It's okay if you don't change the oil in the automatic transmission, but if you change it, there will be problems." This has led to many car owners feeling confused about this.
In fact, oil change is a normal maintenance item of automatic transmission, and there must be only benefits and no disadvantages for the gearbox, so why is there a saying that "a change will cause problems"? I think there are two main reasons: oil suitability and operation standardization.
Oil adaptation. Automatic transmission fluid serves two main purposes: lubrication and power transfer.
Needless to say, lubrication, this function is relatively simple to implement, and the requirements for oil products are not high. The focus is on the transmission of power. For example, the hydraulic torque converter and the actuator of the shift mechanism rely on the transmission oil to transmit power to the medium. At this time, the viscosity and temperature characteristics of the oil will affect it.
Moreover, there are many wet clutch plates in the automatic transmission that transmit power by friction, and these friction plates are also soaked in the transmission oil, and the friction of the oil will also affect the effect of power transmission.
If the oil characteristics do not match the original manufacturer, it is easy to lead to a decrease in the quality of the shift, resulting in problems such as shift stuttering.
Degree of operational compliance.
Changing oil in a manual transmission is simple because it has a simple structure and doesn't have too many complicated systems, so it's almost impossible to make a mistake when changing the oil. The automatic transmission is different, the internal structure is complex, the system is numerous, and it is really possible to have problems if you do not operate according to a reasonable process.
For example, adding too much oil to the gearbox will cause the oil to be continuously stirred and produce bubbles, which will cause abnormal pressure in the hydraulic mechanism. Running out of oil in the gearbox will cause the oil pump to sometimes fail to absorb oil, and it may also cause the oil temperature to be too high, which will naturally cause problems in the transmission.
Because the volume of transmission oil will change with temperature, the original operation process will require the oil level to be checked at a certain temperature, so that the oil volume is closest to the original calibration value, and the probability of problems is the lowest.
In addition, there may be some vacant positions in the oil channel after the transmission oil is emptied, so you should start the vehicle and run in each gear for a period of time to allow the oil to fill the entire oil channel, and then check the oil level again to ensure that the oil level is the most accurate. In reality, many oil change operations do not pay attention to these details, and the probability of problems is naturally higher.
In addition, in recent years, it has been particularly popular to change the oil of the circulating machine, but the oil change of the circulating machine is actually not as tall as imagined. On the contrary, it has brought a lot of negative factors, such as the lack of maintenance of the machine, resulting in different types of oil pollution, circulating flushing to achieve complete replacement, resulting in excessive oil consumption per transmission, increasing costs, and the circulation machine is only an auxiliary, but some people regard it as a fully automated standard, foolish use, completely dependent on the machine, which will inevitably lead to an increase in the probability of risk.
In general, the automatic transmission oil change is not so mysterious, as long as it is operated in full accordance with the manufacturer's standard process, no matter what old car you have, there will be no abnormality after the change.