Your car's transmission fluid is very important to the overall function of the transmission itself. This fluid not only keeps all the gears and chains running smoothly but also keeps the system cool so that there is less unnecessary friction.
Changing the fluid and getting a full fluid flush are very different; when fluid is changed, it is drained out of the pan that holds it in the transmission system. However, there is still fluid inside the cooler lines, the torque converter, and other areas of the transmission system. A full flush is just that; it flushes out all fluid from the transmission system and then new fluid is added. When should you have a full flush done versus just changing the fluid? Note the following.
1. Changing fluid
It's typically recommended that most cars have their transmission fluid changed every two years. Many people reason that changing the fluid alone will still leave sediment and debris in the transmission system and this will simply contaminate the new fluid as it circulates through the transmission. This is certainly true, but consider that there is usually not so much debris that builds up every two years that you need a full flush more often than recommended. The new fluid, without debris and sediment, will also help to dilute the debris that is in the old fluid, and the transmission should run fine.
2. Fluid flush
A fluid flush is typically recommended every three years for most cars. While changing the fluid is often good for a few years, by the time your car has been on the road for this third year, that debris may then start to damage the transmission system and dilute your new fluid. While you don't want to assume that you need a full fluid flush every year, you also don't want to put off having this done as recommended either.
3. When the transmission acts up
Something else to consider about a fluid flush versus adding new fluid is that sometimes a full flush can help to address certain transmission problems. If your car's transmission seems to stick between gears or the shifter itself is difficult to move, this can be the result of sediment and debris in the transmission itself. While a full flush will not fix every problem in the transmission, if you notice these problems and know that you've been relying on fluid changes rather than a full flush service, this may be the first place to start when it comes to addressing these problems.
If you have more question, contact a transmission service.