2000 GMC Sierra 1500 Pickup Owner's Manual - Page 326

yellowblue Manual Transmission Fluid When to Check A good time to have it checked is when the engine oil is changed. See your maintenance schedule to find out when to change your transmission fluid. 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. Be sure to get an accurate reading if you check your transmission fluid. Check the fluid level only when your engine is off, the vehicle is parked on a level place and the transmission is cool enough for you to rest your fingers on the transmission case. How to Check Because this operation can be a little difficult, you may choose to have this done at your GM dealership service department. If you do it yourself, be sure to follow all the instructions here, or you could get a false reading. 6-23