Why Do 4S Stores Not Advocate for Using a Circulation Machine to Change Oil?

[McGia]

Because during the replacement process, a large amount of transmission fluid is required, resulting in higher costs and longer time consumption. When using a circulation machine to change oil, the oil pump continuously injects new oil into the transmission, while the oil extraction tube continuously draws out old oil from the transmission's drain port. By controlling the equal amount of oil added and drained, the total amount of fluid inside the transmission is maintained. There are three methods to change transmission oil: 1. Gravity oil change: Similar to changing engine oil, this method is the simplest and most economical, generally requiring only 3 to 5 liters of transmission fluid. The downside is that gravity draining cannot completely remove all the old oil, only about one-third of the original fluid. 2. Circulation machine oil change: A transmission circulation machine is connected to the transmission's oil circuit interface, with new oil added to the machine. The new oil pushes out the old oil from the transmission, requiring about 12 liters or even more transmission fluid. The more fluid used, the cleaner the transmission becomes. The advantage is thorough oil replacement, while the drawback is the time-consuming process. 3. Removing the transmission oil pan for oil change: The benefit is the ability to clean the transmission oil filter and achieve a relatively thorough replacement.