What is the best material to lubricate a door lock?

The best material to lubricate a door lock is a graphite-based lubricant. Graphite is dry and won't attract dust or dirt, preventing buildup that can cause the lock to jam. Avoid using oil-based lubricants, as they can attract debris and gum up the lock mechanism. Silicone spray can also be a good alternative for lubrication without the mess of oil.