What oil (lubricant) to use for door locks and safe locks [View all]
Everyone knows about WD-40. But what you may not know is that WD-40 is not a lubricant, it's a solvent. Now, that's great if you want to get the gunk off of a lock or to free up some of the parts inside. But that's only the first part. Next you have to replace the lubricant you just removed. What I don't recommend is any lubricant that contains graphite. Graphite is great at making parts work smoothly, but the graphite will also dry out over time and gunk up the works. It also leaves that nasty black residue over everything.
So, what I recommend is a super lubricant that will free up the parts without leaving the black gunk behind. There are a couple very superior lubricants that locksmiths and safe technicians use. "Houdini" is one of them. The other, more expensive, alternative is "Tri-Flow. I use two types of Tri-flow - spray for gross penetration of lock parts, and "pinpoint" for precise applications, like on safe locks. I've included two links for you to compare.
https://www.triflowlubricants.com/all-products/
http://www.houdinilocklube.com/