Solid graphite and very sparingly should be used with these ignition lock cylinders. Again I stress, a little goes a long way. Use as much as you feel like for trunk and door cylinders. It's the electrical component to the ignition that makes using lubricants, of any type, potentially risky.
Aside from that, the point of the post was that it was the keys that were the actual cause of the issue. Lubricating the cylinder actually made matters worse overall and was extremely temporary for the little bit it did help.