Igition switch problem.
 

I've been reading over on LS1 about people having problems with the switch on new GTO's. Well it happened to me today on my 04 with 22k miles on it. It was 95 degrees in a hambutger joint parking lot and the ignition would not bunge. I started walking to a parts store while my buddy kept fooling with it. He got it cranked while I was in the store.
Now this is Not what you want to do. The counter guy sold me some powdered graphite. I drove striaght home and and squeed the graphite into the ignition switch and it gummed it up so bad I couldn't get the key in even part way. I spend over an hour squrting WD 40 in the lock and wiping the gunk off the key.
Now this worked. I sprayed WD 40 in the lock and blow it in with computer air cleaner.
I let it soak about three hours and when I tried it again I pulled on the steering wheel lock hard. Thank God it cranked. It feels free now. Wish me luck.

Weight on a key chain could in time cause problems with the key cylinder, or a wearing of the key itself. All those keys many have dangling on the hoop adds weight. When the key is in the cylinder the weight of all those other keys and or other items on the key chain is pulling down on the key fob and putting pressure on the key in the cylinder. All the added weight can cause a wearing problem inside the cylinder, and or cutting a grove or deep scratches in the key. To avoid this possible problem, only have the car's keys on that chain.

The best choice for lube in the cylinder is graphite. Graphite is a dry lube and bonds to metal surfaces causing a slick surface. Graphite is available in spray, and powder. I would use spray and not powder in a cylinder. The powder will cause a packing action if used too heavy. Any type of grease can be easily transfered to your pants pockets, and lint, and dirt will find its way into the cylinder sticking to grease. This in time will cause a gunky build up. WD-40 and a like will attract lint as well in time.

The best fix for the well documented ignition switch problem is to remove the entire assembly and take a dremmel tool to the channel that the spring loaded pawl rides in.

If lube sprayed in the tumblers freed it up, it was a fluke because the trouble area cannot really be reached through the opening.

If some action is not taken its a matter of when, not if. Hopefully you will not be stranded somewhere.