When it comes to engine maintenance, most car owners are well aware of the basics—but how many actually pay attention to proper automatic-transmission maintenance? And when it comes to changing the automatic-transmission fluid, do people really know the right way to do it?

Q: 
How often should transmission fluid be changed?

A: 
The replacement interval for automatic transmissions is two years; manual transmissions require replacement even sooner.

For automatic transmissions, the oil should typically be changed every 40,000 to 60,000 kilometers, or at least once every two years. For manual transmissions, the interval is usually shorter; just follow the recommendations in the vehicle’s maintenance manual.

If the transmission fluid is not changed for an extended period, its lubricating and heat-dissipating capabilities will deteriorate, causing the fluid temperature to rise excessively and accelerating internal wear. The most noticeable symptoms are less smooth gear shifts with pronounced jerking, and in some models, increased fuel consumption as well.

Gravity Oil Change 
The engine flywheel drives the automatic transmission torque converter, which in turn powers the oil pump to draw automatic transmission fluid (ATF) from the oil pan and deliver it, as shown in Figure 1 below:

The oil pump delivers ATF working fluid to the valve body: one circuit pressurizes the clutch plates of the automatic transmission’s pistons, while the other supplies oil to the torque converter to drive the turbine. The heated ATF is then routed to the radiator for cooling before returning to the oil pan, completing a continuous circulation loop.

When the engine stalls, the automatic transmission ceases to operate, causing the oil pump to come to a standstill and halting the circulation of automatic transmission fluid. Consequently, the fluid that was previously circulating through the valve body, pistons, torque converter, radiator, and cooling lines also abruptly stops flowing, and this fluid can no longer return to the oil pan.

If you unscrew the drain plug on the oil pan to change the oil at this point, you will only be able to drain the oil stored in the pan. This oil-change method is called “gravity oil change.”

Oil Change for the Circulating Pump

Oil changes using a flush-and-replace machine leverage specialized equipment to generate pressure, enabling a dynamic replacement of the transmission’s lubricant from both the main oil lines and the cooler lines. Although this method is relatively time-consuming—typically taking about an hour—the key advantage is its thoroughness: it can remove more than 95% of the old fluid and effectively clean out sludge and metal particles accumulated inside the automatic transmission. With this approach, the oil-change interval can be extended to 40,000–60,000 kilometers. Many car owners worry that such a high-pressure flush might cause significant damage to the transmission; however, aside from the higher cost, flush-and-replace oil changes offer numerous other benefits.

During the oil-change process in the circulating unit, the transition between the old and new oil can be clearly observed through the sight glass: the color of the old oil gradually changes from deep black to red, until the colors of the old and new oil become identical.

Summary:

Is your car’s automatic transmission in good condition?

What is the optimal maintenance interval for automatic transmission servicing?

1. For ZF and other European automatic transmission fluids, the first oil change is recommended at 60,000 kilometers or two years.

II. For Aisin and other Asian automatic transmission fluids, the first oil change is recommended at 40,000 kilometers or two years.

3. For general-purpose and other American-made automatic transmission fluids, the first oil change is recommended at 40,000 kilometers or two years.

Note: For any automatic transmission that has undergone repair, we recommend a maintenance service every 20,000 kilometers or once a year.

Golden Globe Lubricants http://www.runhuayou.cn/