How to Change the Transmission Fluid in a Blazer

by Paul VaughnUpdated November 07, 2017

Items you will need

  • 12 gallons of specific transmission fluid for the year/model of your Blazer

  • 12-gallon drain pan

  • Crescent wrench

The Blazer has an automatic transmission that operates using hydraulic power. Pressure created in the transmission shifts through the drive gears. The driver does not have to shift the Blazer by hand, making the driving experience much easier.

Allow the engine to cool down completely.

Place the drain pan under the transmission.

Locate the drain plug on the bottom of the transmission fluid reservior. The reservior is located under the engine, forward of the oil pan.

Use the crescent wrench to loosen and remove the drain plug.

Allow the transmission to drain until there is only an occasional drip.

Use the crescent wrench, turning clockwise to reinstall the drain plug.

Open the hood and locate the transmission dipstick. It is located next to the oil dipstick.

Remove the dipstick and insert the funnel into the hole.

Add 5 gallons of transmission oil that is the right type for your year/model Blazer.

Start the engine and allow it to come up to operating temperature.

Use the funnel to slowly add a gallon of fluid at a time, checking the level with the dipstick frequently until it reaches the full/hot level. Reinsert the dipstick. The job should take about 30 minutes.


Remember to reinstall the drain plug to prevent leaking fluid. Make sure the engine is at operating temperature before adding fluid. Do not overfill the transmission. This will cause overpressure and costly repairs.


Do not drain the fluid until the engine is cool. Hot fluid will cause severe burns. Use hand tools properly. Failure to do so can cause injury and equipment damage.

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