(page P10 Cautions and Notices)
C6 2006 Service Manual states:
Fastener Notice:
Use the correct fasteners in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paint, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners to avoid damage to parts and systems.