Is changing the transmission fluid filter necessary?

Changing the filter is not always necessary. Some filters are simple metal mesh screens that can be inspected for debris, cleaned, and reused if they are not too contaminated. But because a transmission filter is made accessible when the transmission pan is removed - and because the filter cost is often minimal - most technicians recommend replacing the filter whenever the pan is removed for a fluid change.

How do I know if my transmission fluid is bad?

There are a few indicators that transmission fluid has gone bad. Unfortunately, many late-model vehicles no longer feature user-accessible dipsticks to check the fluid. Instead, many transmissions are considered to be unserviceable by the vehicle owner. If your transmission does have a fluid dipstick, you can check for the following signs of deteriorating fluid. For instance, clean transmission fluid appears red or pink. If it looks dark brown or black, it might be bad. Also, if the fluid has overheated, it might have a “burnt” smell. In either case, it is likely that the fluid needs to be changed.

What happens if you don’t change your transmission fluid?

The fluid inside a transmission works to lubricate and cool the moving parts inside. It also transfers hydraulic energy to make your transmission function properly. If you don't change the fluid regularly, the fluid will eventually become contaminated and break down chemically. Once this happens, it won't protect the moving parts from wear the way it should. It may also cause malfunctions inside the transmission, and it can cause the transmission seals to degrade and leak. Ultimately, this will lead to reduced fuel efficiency and horsepower at best, and a transmission that fails prematurely at worst.