How To Change Automatic Transmission Fluid on Porsche 911 (1999-2001)

Maintenance Interval 9 Years or 90,000 Miles (144,000 Kilometers)
Estimated Dealer Cost $1000
Estimated Independent Mechanic Cost $650
Estimated DIY Cost $120
Repair Time 3 hours
DIY Difficulty Medium

Changing your automatic transmission fluid (ATF) and transmission filter is important to keep your drivetrain smooth. While performing this service isn’t technically hard, filling the transmission fluid to the precise level is difficult without some experience. Therefore, we do not advise you attempt to do-it-yourself unless you are comfortable working on cars.

Even if you don’t feel comfortable performing this service yourself, you can still save a bunch of money by purchasing the parts required online and paying an independent mechanic for just the labor. For an overview of the procedure, check out the procedure from the YouTube channel, Road and Race. While the video covers the procedure on a Porsche 986 Boxster, the process is nearly identical for the 996. You can find detailed instructions below.

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Torque Specs & Fluid Capacities:

ATF Capacity: 4.0 liters (measured when ATF is between 86-104°F)
17m hex Fill plug: 59 ft-lbs
8mm hex drain plug: 30 ft-lbs
Transmission oil pan bolts: 6 ft-lbs
Transmission filter bolts: 4.5 ft-lbs
Aluminum crossmember bolts: 48 ft-lbs

Step-by-Step Instructions:

Step 1: Prepare your vehicle and work area

  • Start with a cold engine.
  • Park your car on a flat surface.
  • Gather required tools and parts.
  • Put on gloves and eye protection.

Step 2: Raise your vehicle off the ground

  • To give yourself enough clearance to work, safely raise your vehicle using a lift or jack and jack stands.
  • ENSURE YOUR CAR IS LEVEL! This is essential to ensure the correct fluid level.
  • NEVER rely on a jack to keep your car up; use jack stands to safely support your vehicle.
  • Also be sure to use wheel chocks to prevent your car from rolling.
  • To lift your vehicle on jack stands, check out this helpful video from CarFanatic.
  • While it is for the Porsche 997, the procedure for the 996 is the same.
  • Once your car is on jack stands, give your car a hard shove to make sure it is secure.

Step 3: Gain access to the transmission oil pan

  • Remove the underbody panels on the bottom of vehicle and just ahead of the engine; these are just held on by Phillips screws and 10mm plastic nuts.
  • To gain access to the transmission oil pan, you will need to remove the aluminum crossmember; remove the 15mm bolts that hold it in place.
  • You should now have access to the transmission oil pan.

Step 4: Remove the transmission oil pan fill plug

  • Locate the fill plug on the bottom of the transmission pan and break it loose with a 17mm hex bit and ratchet. Do not fully remove the fill plug.
  • Place a drain pan under the fill plug in case ATF comes out, then remove the fill plug.
  • Note: If you cannot get the fill bolt off, STOP and do not proceed with the procedure as you will not be able to fill your transmission with new ATF.

Step 5: Drain the automatic transmission fluid

  • Locate the 8mm drain plug located on the bottom of the transmission oil pan.
  • Break the drain plug loose, but don’t fully remove it.
  • Place a drain pan underneath the drain plug, then remove the drain plug; be sure to catch the drain plug so it doesn’t fall into the drain pan.
  • Clean off the drain plug threads and reinstall it along with a new sealing ring (see parts section).
  • Torque the drain plug to 30 ft-lbs.

Step 6: Remove the transmission oil pan

  • Place drain pan below the transmission oil pan.
  • While supporting the transmission oil pan (to avoid damaging anything), remove the T30 Torx bolts that hold the transmission oil pan in place.
  • Carefully pull off the transmission oil pan and watch out for any ATF that comes out.
  • Inspect the mating surface where the transmission oil pan and transmission meet; if there is any residue or leftover gasket material, clean it off.
  • With the transmission oil pan off, take a look at the fill plug baffle so you will be able to route your fluid pump hose through it accordingly.
  • Clean the transmission oil pan thoroughly with a degreaser, then dry it off.

Step 7: Install the new transmission filter

  • The transmission filter is held on by T30 Torx bolts.
  • Remove these bolts, then pull out the old transmission filter.
  • Pour any fluid inside the transmission filter into your drain pan.
  • Apply a thin layer of new ATF onto the rubber seal on the transmission filter to help it seat properly.
  • Install the new transmission filter and torque the bolts to 4.5 ft-lbs.

Step 8: Reinstall the transmission oil pan

  • Place your new gasket on the transmission oil pan.
  • Install the new gasket and transmission oil pan back onto the transmission.
  • Screw in the T30 Torx bolts by hand, but don’t tighten them.
  • Torque the T30 Torx bolts to 4.5 ft-lbs or just slightly by hand; be sure to use a criss-cross pattern as shown in the photo to ensure the gasket is properly seated.
  • DO NOT over torque the bolts or you can create a leak in the gasket.
Reinstall the transmission oil pan

Step 9: Fill the transmission with an initial amount of fresh ATF

  • As shown in the video from BleeinJeep, attach the fluid pump to your container of ATF and route the other hose into the transmission oil pan fill hole; be sure to route the hose through the internal baffle or you will not be able to get the new ATF into the pan.
  • Pump new ATF fluid into the transmission until fluid begins to drip out of the fill port.

Step 10: Add additional ATF and ensure you reach the correct level

  • To ensure the ATF is at the correct level, your vehicle must be level and the ATF level must be measured once the fluid reaches between 86-104°F (30-40°C).
  • With the brakes engaged, start your car and cycle the transmission from PARK to DRIVE and then REVERSE. Pause in each gear for 10 seconds.
  • Go back under the car and add more ATF if fluid isn’t dripping out.
  • Once fluid is dripping out, use a pyrometer to measure the temperature of the oil pan.
  • When the transmission oil pan reaches the target temperature and ATF is barely dribbling out, you’ve reached the right level.
  • Before the transmission oil pan reaches 104°F (40°C), reinstall the fill plug along with a new o-ring and torque it to 59 ft-lbs.
  • Note: If the ATF pan exceeds the target temperature, install the drain plug, turn off the engine, and allow the ATF to cool back down.

Step 11: Reinstall everything and lower your vehicle

  • Reinstall everything in reverse.
  • Torque the 15mm bolts that hold the aluminum crossmember to 48 ft-lbs.
  • Just hand tighten the fasteners for the underbody panels.
  • Lower your vehicle.
  • Save your old ATF in a contain, so you can drop it at your local auto parts store to recycle.
  • Clean up your work area and put away your tools.

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