1998 GMC Suburban Owner's Manual - Page 314

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). Let the engine run at idle for three minutes or more. Then, without shutting off the engine, follow these steps: 2. Push it back in all the way, wait three seconds and then pull it back out again. 3. Check both sides of the dipstick, and read the lower level. The fluid level must be in the COLD area for a cold check or in the HOT area or cross-hatched area for a hot check. 4. If the fluid level is in the acceptable range, push the dipstick back in all the way; then flip the handle down to lock the dipstick in place. 1. The red transrnission dipstick is located at the rear of the engine compartment,on the passenger's side. Flip the handle LIP and then pull out the dipstick and wipe it with a clean rag or paper towel. 6-22