Pontiac 2005 Bonneville Owner's Manual page 290

Then, without shutting off the engine, follow these steps:
1. After removing the engine air cleaner/filter assembly
to reach the transaxle fluid cap, turn the cap
counterclockwise to remove. 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.
5-30
The transaxle fluid cap is
located next to the radiator
hose and below the
engine air cleaner/filter
assembly on the driver's
side of the vehicle.
See Engine Compartment
Overview on page 5-12
for more information
on location.
3. Check both sides of the dipstick, and read the
lower level. The fluid level must be in the
cross-hatched area.
4. If the fluid level is in the acceptable range, push the
dipstick back in all the way and turn the handle
clockwise. Reinstall the engine air cleaner/filter
assembly.