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Transmission Filter Maintenance 101: When To Change It

Transmission cutaway for transmission filter maintenance

Automatic transmission filter maintenance can sometimes feel a little more like voodoo than science. With so many automakers advertising “lifetime” transmission fluids that never need to be swapped out, you might think that the same also goes for the filter inside these gearboxes.

The actual truth is a little more complex than that. Do you really need to change your gearbox’s filter? Here’s what you need to know.

What Does a Filter Do?

As the miles whiz by, your automatic transmission is under a lot of stress from the heat that is generated during normal operation. Internal gear wear can sometimes result in metal shavings floating around in the transmission fluid as your vehicle gets older. In order to keep things shifting smoothly, the transmission filter sifts out the metal and keeps it from causing problems. Because many gearboxes aren’t completely sealed — there are breather vents, a filler tube and a level check tube — sometimes dirt and other foreign particles can find their way inside the fluid as well, where they are also cleaned out by the filter.

When to Change?
Automatic transmission

Realistically, you’re not going to crack open your transmission to check if the filter is clogged or not; it’s typically not the most convenient part to access. What you can do is replace the filter at the recommended transmission fluid change interval that you find in your owner’s manual, because you’ll most likely have to drop the transmission pan to do the fluid swap. Sometimes a vehicle will also keep track of fluid life inside its on-board computer and give you a warning when you are nearing its useful end.

Alternatively, you can check for two other signs that it might be time for a transmission filter change. The first is if your transmission fluid starts to smell burnt, or if it turns a dark color. These are indications that it’s no longer as effective as it could be and should be changed — the filter needs to go too, as it has probably soaked up a lot of the old fluid over the course of its lifespan. Another indication is if you start to experience unusual transmission behavior, either in the form of clunky gearshifts or unusual noises. These can also be clues that the filter and fluid need to be replaced.

Can You DIY?

As explained above, most of the time replacing a transmission filter is spent removing the transmission pan and draining the fluid. It’s not a difficult process, but it can definitely be a messy one. If you are comfortable with removing the pan, popping out the old filter and installing a new one, and then using the correct pan gasket to reseal the transmission, then it’s really only a matter of a few nuts and bolts. Some vehicles have more complicated transmission filter replacement procedures, however, so make sure you do your research before getting started.

Check out all the maintenance parts available on NAPA Online or trust one of our 17,000 NAPA AutoCare locations for routine maintenance and repairs. For more information on transmission filter maintenance, chat with a knowledgeable expert at your local NAPA AUTO PARTS store.

Photo courtesy of Wikimedia Commons

Benjamin Hunting View All

Having been bitten by the car bug at a young age, I spent my formative years surrounded by Studebakers at car shows across Quebec and the northeastern United States. Over ten years of racing, restoring, and obsessing over automobiles lead me to balance science writing and automotive journalism full time.  I currently contribute as an editor to several online and print automotive publications, and I also write and consult for the pharmaceutical and medical device industry.

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