GMC 1996 Sonoma Owner's Manual page 240

Then, without shutting off the engine, follow
these steps:
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.
1. Flip the handle up and then pull out the dipstick and
wipe it with a clean rag or paper towel.
2. Push
it back in all the way, wait three seconds and
then pull it back out again.
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 i n place.
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