GM Service Manual Online
For 1990-2009 cars only

When to Check and Change Automatic Transmission Fluid

A good time to check the automatic transmission fluid level is when the engine oil is changed.

Change the fluid and filter at the intervals listed in Additional Required Services, and be sure to use the transmission fluid listed in Recommended Fluids and Lubricants.

How to Check Automatic Transmission Fluid

Because this operation can be a little difficult, you may choose to have this done at the dealer/retailer service department.

If you do it yourself, be sure to follow all the instructions here or you could get a false reading on the dipstick.

Notice: Too much or too little fluid can damage your transmission. Too much can mean that some of the fluid could come out and fall on hot engine parts or exhaust system parts, starting a fire. Too little fluid could cause the transmission to overheat. Be sure to get an accurate reading if you check your transmission fluid.

Wait at least 30 minutes before checking the transmission fluid level if you have been driving:

    • When outside temperatures are above 90°F (32°C).
    • At high speed for quite a while.
    • In heavy traffic -- especially in hot weather.
    • While pulling a trailer.

To get the right reading, the fluid should be at normal operating temperature, which is 180°F to 200°F (82°C to 93°C).

Get the vehicle warmed up by driving about 15 miles (24 km) when outside temperatures are above 50°F (10°C). If it is colder than 50°F (10°C), you may have to drive longer.

Checking the Fluid Level

Prepare the vehicle as follows:

  1. Park the vehicle on a level place. Keep the engine running.
  2. With the parking brake applied, place the shift lever in P (Park).
  3. With your foot on the brake pedal, move the shift lever through each gear range, pausing for about three seconds in each range. Then, position the shift lever in P (Park).
  4. Let the engine run at idle for three to five minutes.

Then, without shutting off the engine, follow these steps:

  1. Locate the transmission fluid cap which is located next to the radiator hose and below the engine air cleaner/filter assembly on the driver side of the vehicle. The cap is marked TRANS FLUID. See Engine Compartment Overview for more information on location.
  2. After removing the engine air cleaner/filter assembly to reach the transmission fluid cap, turn the cap counterclockwise to remove. Pull out the dipstick and wipe it with a clean rag or paper towel.
  3. Push it back in all the way, wait three seconds, and then pull it back out again.

  4. Object Number: 1631894  Size: B3
  5. Check both sides of the dipstick and read the lower level. The fluid level must be in the cross-hatched area.
  6. If the fluid level is in the acceptable range, push the dipstick back in all the way and turn the handle clockwise.
  7. Reinstall the engine air cleaner/filter assembly.

How to Add Automatic Transmission Fluid

Refer to the Maintenance Schedule to determine what kind of transmission fluid to use. See Recommended Fluids and Lubricants.

If the fluid level is low, add only enough of the proper fluid to bring the level into the cross-hatched area on the dipstick.

  1. Pull out the dipstick.
  2. Using a long-neck funnel, add enough fluid at the dipstick hole to bring it to the proper level.
  3. It does not take much fluid, generally less than one pint (0.5 L). Do not overfill.

    Notice: Use of the incorrect automatic transmission fluid may damage the vehicle, and the damages may not be covered by the vehicle's warranty. Always use the automatic transmission fluid listed in Recommended Fluids and Lubricants .

  4. After adding fluid, recheck the fluid level as described under "How to Check Automatic Transmission Fluid," earlier in this section.
  5. When the correct fluid level is obtained, push the dipstick back in all the way and turn the handle clockwise.