How to Install a New Automatic Transmission Oil Pan Gasket and Filter

The fluid in your vehicle's automatic transmission is different from the oil in the engine. Transmissions operate with higher pressures, and the fluid in them is thinner. Maintenance schedules for automatic transmissions are also different from engines, with a transmission fluid change recommended every 50,000 to 75,000 miles. We'll walk you through the process of changing the fluid and filter (where applicable).

Source | Mike Aguilar

Should You Flush or Change Your Transmission Fluid?

Up until fairly recently, mechanics didn't recommend flushing your transmission fluid because we didn't know about it. The recommended service was to drop the pan, replace the filter, and refill the transmission after replacing the pan and gasket. This evolved to also drilling a small hole in the torque converter to change the seven to 12 quarts it contains that don't drain out when you remove the oil pan. Some automatic transmissions are what manufacturers like to call "sealed-maintenance free"—something that is a misnomer because all oils degrade over time and require changing. These transmissions require different service procedures, which won't be covered here.

Carquest Trans Filters Transmission Filter, Advance Auto Parts

Fast-forward a couple of decades, and some engineer came up with the idea of using the transmission's pump to replace all the old fluid with new fluid. Doing this comes with risks, though, if you haven't been scrupulous with your transmission maintenance procedures. Transmission flushing can surface problems that the old, unchanged fluid was masking, because flushing removes the grit-filled fluid that was giving the internal parts the friction they needed to continue functioning. In fact, many shops now refuse to flush or replace transmission fluid on high-mileage vehicles, for just this reason.

If your transmission fluid is black and makes you sick to smell it, consider getting a bottle of Lucas Oil Transmission Fluid Treatment to help stave off internal slippage. Just realize that if you've waited to change your transmission fluid until it's black and sludgy, you're more than likely going to be need to replace the transmission before too long. You'll quickly recognize the burnt-toast smell from worn, tired ATF.

Beck/Arnley Transmission Filter Kit | Advance Auto Parts

Vehicle System
Powertrain / Drivetrain
Skill Level
Beginner

This is a good project for new DIYers

Intermediate

This is a project that needs some know-how

Time to Complete
1 - 2 Hours
    Pro Tip
    Oil Pan

    The torque converter in your transmission can hold up to 14 quarts of fluid. None of this fluid drains out when the pan is dropped. To combat this, you can purchase a torque converter plug bolt and insert it into a hole you drill on the front (engine side) of the torque converter after removing the splash shield/inspection plate. If you choose this route, be sure to refill the transmission with sufficient fluid to completely fill it. This isn't for the fainthearted, though, as you are drilling into a vital component of your transmission, and caution must be exercised while drilling. Source | Mike Aguilar

  1. Raise the vehicle enough to crawl under the transmission. This won't require doing anything with most front wheel drive vehicles, as the transmission is up front, although it does make it easier.

    Oil Pan

    Source | Mike Aguilar

  2. Place the drain pan beneath the transmission oil pan. Remove the drain plug, if so equipped. Allow the fluid to drain.

    Oil Pan

    Source | Mike Aguilar

  3. Loosen and remove the bolts around the transmission pan, leaving the bolts in the four corners in but loose. Allow the rest of the fluid to drain.

  4. Use a small, flat screwdriver to separate the oil pan from the transmission case. Be careful here to keep the four corner bolts in but loose so the pan doesn't fall and make a huge mess.

    Oil Pan

    Source | Mike Aguilar

  5. Use a small screwdriver, wrench, or socket (as required) to remove the transmission oil filter, if so equipped. Don't forget the filter gasket.

    Oil Pan

    Source | Mike Aguilar

  6. Paying attention to orientation and the seal/filter gasket, replace the transmission filter. Don't over-tighten the bolts/screws.

    Oil Pan

    Source | Mike Aguilar

  7. Use a gasket scraper/remover to remove the old transmission oil pan gasket from the pan and the transmission.

    Oil Pan

    Source | Mike Aguilar

  8. Thoroughly clean the inside of the pan, paying attention to any magnet that may be present. Be on the lookout for any metal shavings or fragments adhering to the magnet.

    Oil Pan

    Source | Mike Aguilar

  9. Place the new transmission pan gasket on the pan and lift the pan into place. Be aware that most transmission pans are not symmetrical, meaning that the gasket will only fit one way—the right way.

  10. Pro Tip
    Oil Pan

    A good spray- or paint-on gasket adhesive will keep the gasket in place and not prove problematic to the transmission later on. Don't, however, use any type of gasket sealer, since fragments of the sealer can come loose and be ingested by the transmission's internals. Also note that you may need to adjust the fit of the pan before replacing it as it may warp during removal. Source | Mike Aguilar

  11. Replace the bolts on the transmission oil pan, working in a star pattern from the corners to keep the pan from cocking. Don't over-tighten these bolts, as the metal of the pan will distort and allow fluid to leak out11. Lower the car back onto the ground if you lifted it.

    Oil Pan

    Source | Mike Aguilar

  12. Locate and remove the transmission dipstick. Place the transmission funnel into the dipstick tube and empty two quarts of the recommended transmission fluid/oil. Be certain to use the right brand and formulation of fluid, as recommended by the manufacturer. At one time, there were only a few varieties of ATF on the market; now there are more than a dozen, custom-blended for specific makes and models. Using the wrong fluid can quickly damage or wreck a transmission.

  13. Start the engine and shift through the gears several times. As you shift, allow the transmission to go into gear before shifting into the next gear.

    Oil Pan

    Source | Mike Aguilar

  14. Once the engine and transmission have warmed up, check the fluid level. Remember, you need the engine running and the vehicle parked on a level surface to do this. Do not overfill the transmission.

Last updated January 30, 2019

Share