The oil plug is located on the bottom of the Oil pan. The best way to learn is to ask your mechanic to show you the location of the different parts of the vehicle the next time you go in for service. They usually don't mind giving you a tour of the underside of you vehicle.
In a 2002 trailblazer it is located on the bottom of the radiator one the passenger side. Every other model year to my knowlege does not have drain plug.
Should be on the rear or side of the oil pan
Behind the Battery in a small pouch.
"Where is the oil plug located for a 2008 Chevy silverado ext cab?"
The 2006 Chevy Trailblazer passenger side rear freeze plug is located near the back of the engine block. The freeze plug will be near the bottom of the engine block.
spark plug
Under the dash
The 2005 Chevy Trailblazer has Coil-On-Plug ignition coils so there are 6 "coil packs". Each one is mounted on top of the spark plug.
in the oil pan
.043
AC Delco iridiums
15mm