1998 GMC Suburban Owner's Manual - Page 313

Checking Transmission Fluid Hot NOTICE: Too much ortoo 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. 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: 0 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 (lO"C), drive the vehicle in THIRD (3) until the engine temperature gage moves and then remains steady for 10 minutes. Then follow the hot check procedures. Checking Transmission Fluid Cold A cold check is made after the vehicle has been sitting for eight hours or more withthe engine off and is used only as a reference. Let the enginerun at idle for five minutes if outside temperaturesare 50 "F (10 "C) or more. If it's colder than 50°F ( 1OOC), you may have to idle the engine longer. Should the fluid levelbe low during a cold check, you must perform a hot check before adding fluid. This will give you a more accurate readingof the fluid level. When outside temperatures are above 90°F (32°C). At high speed for quite a while. 0 0 0 In heavy traffic -- especially in hot weather. While pulling a trailer. Checking the Fluid Hot or Cold e Park your vehicle on a level place. Keep the 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). See"Checking Transmission Fluid Hot" in the Index. engine running. 0 With the parking brake applied, place the shift lever in PARK (P). 6-21