There was a thread about six weeks ago on the best lock lube. Most of us said Dry Graphite. It's what I've always used, had professional locksmiths tell me to use, etc. Some smarter folks than I bucked the cw and suggested axle grease. Now that I have IN DEPTH experience with what the dry graphite really does in car doors, I'll never use it again. Pics and details below. It might be suitable for indoor use, but not at all on a car exposed to weather.
Summary: What I found was that after just a few weeks with a clean cylinder lubed with dry graphite, and steady early-winter PNW rains, it had turned to a sticky glue and was not lubricating and actively increasing cylinder wear. There were no contaminants in the cylinder. Tonight I rebuilt the cylinder after stripping it again and lubricating with SuperLube. Massive improvement.
Full Story: I have been reconditioning a 2003 Honda Civic for a new driver to use as his first car (step-son). The car is in good shape, 182k miles. Our close friends bought the car from a mechanic friend of theirs, and it showed lots of good repairs done properly - VCGs, axles, shocks, etc. I didn't have to do any heavy work with it, but clean up some common Honda problems like failing locks (very common), rocking drivers seats (very common), leaking cheap plastic cylinder head plugs (re-occurring problem), in-op airbag system (constant problem). If GM made this, people would scream. But hey, it's Honda, so they get a pass. I don't exactly know how that works...
The lock issues were a real treat. I had to pull all of the cylinders as none worked well. I figured out the coding sequences (there are three - trunk pattern for valet key, side doors, and ignition (added security). I re-tumbled/pinned all the cylinders tossing out any questionable at all tumbler and using a new one. The ignition got all new pins just because. I also had a new transponder key made at Ace Hardware, which was a real chore but not obscene like at the local incompetent dealership (Honda of Bellevue - truly a cast of incompetents). At Ace it was $88 with tax. Some (not all) Aces can do transponder keys, as can many other hardware stores and some Walmarts.
After getting everything working well, my step-son complained the driver's door lock was not "breaking in" like I told him it would (new key, new pins). I checked and he was right, something was off as it was getting worse, not better. Tonight I finally pulled the cylinder out and found that I had mis-keyed the last double-width tumbler, which differentiates the valet key (trunk) and door/ignition key. My bad. Fortunately I made detailed keying sequence notes so I could figure out the mistake really quickly.
BUT - what shocked me was how hard the other, good tumblers were to turn, and sticky they were. I had cleaned out the cylinder body and any springs or tumblers I re-used with solvent. I then dried them and cleaned again with soap and water. I dried them all and re-assembled the whole thing with only clean materials and dry graphite. The 1st pic below is the tumblers AFTER soaking in solvent. I couldn't even get the tacky graphite off with very fine sandpaper, I had to get out a wire wheel.
I re-assembled the cylinders with SuperLube and what a difference. Also, it made assembly much easier as it held the springs and tumblers in place during re-assembly. I stuffed the cylinder full of SuperLube to let the key drive it everywhere and seal out the rain/water that might try to work in. On the other cylinders, I'm going to get a small syringe with a tube and inject a healthy amount in each and let it work through vs. pulling them all and flushing again. Will repeat on our other cars as I had added some dry graphite lube to all their cylinders, also.
