2005 Chevrolet TrailBlazer Owner's Manual - Page 345

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's colder than 50_F (10_C), drive the vehicle in THIRD (3) until the engine temperature gage moves and then remains steady for 10 minutes. A cold fluid check can be made after the vehicle has been sitting for eight hours or more with the engine off, but this is used only as a reference. Let the engine run at idle for five minutes if outside temperatures are 50_F (10_C) or more. If it's colder than 50_F (10_C), you may have to idle the engine longer. Should the fluid level be low during this cold check, you must check the fluid hot before adding fluid. Checking the fluid hot will give you a more accurate reading of the fluid level. Checking the Fluid Level Prepare your vehicle as follows: D Park your vehicle on a level place. Keep the engine running. in PARK (P). D With the parking brake applied, place the shift lever D 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 PARK (P). D Let the engine run at idle for three minutes or more. 6-19