If you are out of warranty do this.
1. From inside the vehicle, spray GM Superlube, PIN 12346241 (in Canada, use PIN 10953474), into the gap between the inner shaft and outer shaft at the steering shaft for about two to three seconds.
2. Start the vehicle and turn the steering wheel 180 degrees and spray into the gap between the inner shaft and the outer shaft again for about two to three seconds.
3. Wipe off any excessive lubricant that may run down the outer shaft with a shop towel.
4. Cycle the steering wheel lock to lock for two complete cycles.
Go here to see where to lube.
http://i45.photobucket.com/albums/f9...go/1971218.gif