2010 GMC Canyon Extended Cab Owner's Manual - Page 298

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 adding it yourself, be sure to follow all the instructions here, or there could be 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: 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). 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 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 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. 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. 6-22