Follow the recommendation in your owner's manual. Or change it every 36,000 miles unless it is a sealed for life transmission.
transmission fluid
Should be Dexron III. However, look on the dipstick, it says on it, at least it does on my 2004 Trailblazer.
The transmission fluid on a Chevy Trailblazer is changed by placing a drain pan under the vehicle, removing the drain plug, and allowing it to empty. The drain plug is then re-installed and fluid added through the filler tube until full.
Aprox 4 1/2 qts.
The transmission fluid should be change every 30,000 miles
I have a 2001 325ci BMW with 150,000 miles. When should I check or change the transmission fluid?
Dexron III Automatic Transmission Fluid
what type of automatic transmission fluid needed for 2004chevrolet trailblazer
when should transmission fluid be changed in a 2006 kia spectra
You should change your automatic transmission fluid in Toyota gearbox at least after every 30,000 miles.
Most GM products, including the 2003 Trailblazer, take Dexron III transmission fluid. However, it is always a good idea to consult the owner or maintenance manual to be certain.
You should always change the transmission fluid according to the vehicle manufacturer's recommendations. However, it is perfectly fine to add fluid as needed between changes.