What do I use to lubricate Ignition key slot?

teflon, or graphite lubricants work best...

 

Really makes a quick job when bleaching your key slot

 

Most of the time the problem isn't the tumbler it's the key. Specifically sharp edges or burrs along the cut edge, smoothing the cut edge with a soft brass wire wheel fixes it many times

 

Don’t use dry graphite lubricant, used that on locks in the house and it gets all over the place. I would use a light amount of a Teflon based lubricant. You might want to try moving your steering wheel a little when you have difficulty inserting the key, to make sure the steering wheel lock isn’t the cause of your problem.

 

This is terrible advice.

OP, you probably don't need to do anything. It's a new truck with new keys. It's tight now, but it'll loosen up with use.