Besides the engine, the transmission is the most expensive part of your vehicle. And like engine oil, the transmission fluid requires periodic replacement. Many automatic transmissions also have an internal filter that needs to be replaced along with the fluid.
The transmission fluid has several responsibilities:
- Transfer hydraulic pressure and force to the internal transmission components
- Help reduce friction
- Transfer excess heat away from high temperature components
- Lubricate internal transmission components
The main threat to automatic transmission fluid is heat. Even if the transmission is kept at the proper operating temperature, the normal operation of the internal parts still create heat. This breaks down the fluid over time and can cause gum and varnish. This can lead to sticking valves, increased fluid breakdown, contamination and transmission damage.
Because of this, it’s important to change your transmission fluid according to the time interval listed in your owner’s manual. This is generally every 2 to 3 years or 24,000 to 36,000 miles. If the vehicle sees frequent severe use, such as towing, the fluid should be changed once a year or every 15,000 miles.
The following steps will show you how to replace the transmission fluid on a conventional transmission with a dipstick.
- Note: Many new vehicles do not have dipsticks. They may also have complicated service procedures or be sealed and completely unserviceable.
Step 1 of 4: Prepare the vehicle
In order to safely and efficiently service your transmission, you need few items in addition to basic hand tools.
- Free Autozone repair manuals - Autozone provides free online repair manuals for certain makes and models
- Jack and jack stands
- Oil drain pan
- Protective gloves
- Chilton Repair manuals (optional)
- Safety glasses
- Wheel chocks
Part 1 of 4: Prepare the vehicle
Step 1: Chock the wheels and set the emergency brake. Park your vehicle on level ground and set the emergency brake. Then place wheel chocks behind the front wheels.
Step 2: Jack up the vehicle. Place the jack under a sturdy portion of the frame. After you have the vehicle in the air, place jack stands under the frame and lower the jack.
If you have any questions as to where to place the jack on your particular vehicle, consult the repair manual.
Step 3: Place a drain pan under the vehicle.
Part 2 of 4: Drain the transmission fluid
Step 1: Remove the drain plug (if equipped). Some transmission pans have a drain plug mounted in the pan. Loosen the plug using a ratchet or wrench. Then, remove it and allow the fluid to pour into the oil drain pan.
Part 3 of 4: Replace the transmission filter (if equipped)
Some vehicles, mostly domestics, have a transmission filter. To access this filter and drain the transmission fluid, the transmission pan must removed.
Step 1: Loosen the transmission pan bolts. To remove the pan, remove all the front and side retaining bolts. Then, loosen the rear retaining bolts a few turns and pry or tap the pan loose.
Allow all of the fluid to drain out.
Step 2: Remove the transmission pan. Remove the two rear pan bolts, pull the pan down and remove its gasket.
Step 3: Remove the transmission filter. Remove all of the filter retaining bolts (if equipped). Then pull the transmission filter straight down.
Step 4: Remove the transmission pickup screen seal (if equipped). Remove the transmission pickup screen seal inside the valve body with a pick of small screwdriver.
Be careful not to nick the valve body in the process.
Step 5: Install the new pickup screen seal. Install the new pickup tube seal on the transmission filter pickup pipe.
Step 6: Install the new transmission filter. Insert the pickup tube into the valve body and push the filter up towards it.
The re-install the filter retaining bolts until they are snug.
Step 7: Clean the transmission pan. Remove the old filter from the transmission pan. Then, clean the pan using brake clean and a lint-free rag.
Step 8: Reinstall the transmission pan. Position the new gasket on the pan. Install the pan and secure it with the retaining bolts.
Tighten the retainers until they are snug. Do not over-tighten the bolts or you will distort the transmission pan.
If you have any doubts, consult the vehicle repair manual for the exact torque specifications.
Part 4 of 4: Put in the new transmission fluid
Step 1: Reinstall the transmission drain plug (if equipped). Reinstall the transmission drain plug and tighten it until it’s snug.
Step 2: Remove the jack stands. Jack up the vehicle in the same location as before. Remove the jack stands and lower the vehicle.
Step 3: Locate and remove the transmission dipstick. Locate the transmission dipstick.
Generally, it will be on the side of the engine near the back and it will have a yellow or red handle.
Remove the dipstick and set it aside.
Step 4: Pour the transmission fluid in. Using a small funnel, pour the transmission fluid into the dipstick.
Consult the vehicle repair manual for the correct type and amount of fluid to add. Most auto parts stores will also be able to provide this information.
Reinsert the dipstick.
Step 5: Allow the engine to reach operating temperature. Start the vehicle and allow it idle until it reaches operating temperature.
Step 6: Check the transmission fluid level. With the engine still running, move the gear selector through each position while holding your foot on the brake. With the engine still running, put the vehicle back in park and pull out the transmission dipstick. Wipe it off and reinsert it. Pull it back out and check that the fluid level is between the hot full and add marks.
Add fluid as necessary but do not overfill the transmission or damage may occur.
- Note: In most cases, transmission fluid level must be checked with the engine running. Consult your owner’s manual for the correct procedure for your vehicle.
Step 7: Remove the wheels chocks.
Step 8: Drive the vehicle and recheck the fluid level. Drive the vehicle a couple miles or so, then recheck the fluid level, adding as needed.
Performing a transmission service can be a dirty and difficult job. If you prefer to have the job done for you, give the experts at YourMechanic a call.
This article originally appeared on YourMechanic.com as How to Change Your Automatic Transmission Fluid and was authored by Mia Bevacqua.