2010 Hummer H3 Owner's Manual - Page 279

Vehicle Care Notice: Too much or too little fluid can damage the 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 checking the transmission fluid. Wait at least 30 minutes before checking the transmission fluid level if you have been driving: . 10-13 Get the vehicle warmed up by driving about 24 km (15 miles) when outside temperatures are above 10°C (50°F). If it is colder than 10°C (50°F), drive the vehicle in 3 (Third) until the engine temperature gauge 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 10°C (50°F) or more. If it is colder than 10°C (50°F), the engine might have to idle longer. Should the fluid level be low during this cold check, check the fluid hot before adding fluid. Checking the fluid hot gives a more accurate reading of the fluid level. Checking the Fluid Level To prepare the vehicle: 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 minutes or more. When outside temperatures are above 32°C (90°F). 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 82°C to 93°C (180°F to 200°F).