How To Change Your Car’s Automatic Transmission Fluid

Changing your car's automatic transmission fluid is just as important as changing the engine oil. Keeping old, dirty fluid in circulation could harm the inner workings of the transmission, shortening its lifespan and putting it at great risk of a premature breakdown.

While you can leave transmission fluid changes in the capable hands of your mechanic, most fluid changes are simple enough to be done in your own driveway. The following shows how you can successfully change your own transmission fluid.

The Tools You'll Need

Changing the transmission fluid requires a few relatively straightforward tools, although there are plenty of optional ones available if you need them. The basic tools you'll need for this job include:

  • A catch pan for capturing the transmission fluid
  • A socket wrench set for loosening the transmission pan
  • A funnel for adding the transmission fluid
  • A replacement transmission fluid filter
  • Ramps or jack stands for keeping your vehicle elevated
  • Wheel chocks to keep your vehicle from rolling

Of course, you'll also need the right automatic transmission fluid. It's very important that you use automatic transmission fluid that's compatible with or specifically formulated for your car's transmission. Using the wrong fluid could result in catastrophic damage and a whopping bill for a transmission repair or replacement. Fortunately, your vehicle owner's manual should have the exact type and amount of transmission fluid your vehicle needs.

Draining the Transmission Fluid

Find a perfectly level spot in your driveway or garage to perform the transmission fluid change. Next, you'll want to roll the front of your vehicle up on the ramps or lift the front with a floor jack and place the jack stand underneath. Place wheel chocks in front of the rear wheels to keep the vehicle from moving.

Next, prepare the work space by placing newspaper underneath where the transmission fluid pan is located. This will keep your driveway from getting stained with transmission fluid. Now you can start changing the transmission fluid:

  • Locate the transmission fluid pan and place the catch pan underneath. If the pan has a drain plug, remove the plug and let the fluid drain into the catch pan. Otherwise, you'll have to loosen the bolts on the pan one by one until the fluid begins to pour out. Keep loosening the bolts until the fluid has completely drained out of the pan. At this point, you should be able to remove the pan completely without making a mess.
  • Take a look inside the pan. Take note of any serious sediment buildup, as it could indicate a problem with your transmission. If the pan features a magnet, check it for any metallic particle or clutch material buildup. You can use a clean cloth and some cleaning solvent to clean the pan and magnet. Locate the transmission fluid filter and replace it with a new, clean filter.
  • Check the transmission fluid pan's gasket before reinstalling the pan. Some pans use a reusable gasket while others require a brand-new gasket or an application of RTV silicone on the lip of the pan prior to reinstallation.
  • Reinstall the pan and make sure each bolt is properly tightened to prevent leaks. If you used the drain plug, make sure it's been reinserted and tightened properly.

Adding New Transmission Fluid

Open the hood and locate the transmission fluid filler neck. Remove the dipstick from the filler neck and insert the funnel. Carefully add the required amount of transmission fluid as specified by the vehicle owner's manual.

Afterwards, reinsert the dipstick, start up the car and let it run for a few minutes to circulate the new fluid through the transmission. Make sure to engage each gear on the shift indicator for a few seconds before putting it back in park. While the engine's still running, check the fluid level on the dipstick. Add as much fluid as required to bring it up to the "full" line.

Once you're done, you can set the drip pan aside for proper disposal, dispose of the newspaper and remove the vehicle from the ramp.

How Often Should You Change Your Transmission Fluid?

Typical intervals for changing your automatic transmission fluid can vary among auto manufacturers. Most experts recommend that fluid changes be done at least every 30,000 miles. Some manufacturers require changes at 60,000 miles while others specify 100,000 miles as the ideal interval, especially if fluid varieties formulated for long life are used. If you use your vehicle for towing or other severe-duty tasks, then it's best to change your transmission fluid every 15,000 miles.