Lubricating Your Locks
The subject of lock lubrication is unusually controversial. Not all lubricants work well with locks. The problem seems to be that some seem to work well when applied, but in the long run may cause more problems than you started with.
The old standby is powdered graphite. Powdered graphite is an excellent lock cylinder lubricant, but can be messy. Use caution if there is light colored carpeting in the vicinity of the lock. Newer lubricants will do the job as well, without the potential mess, and with additional benefits.
What you do NOT want to use is any lubricant containing petroleum distillates. These "oily" lubricants will attract and hold dust and dirt, forming a sticky mess over time. Additionally, these lubricants can react negatively with rust inhibiting finishes used by manufacturers on internal parts of locks and other door hardware. Again, over time, a sticky film may develop and cause the sort of problems a good lubricant would prevent.
Because of the possibility of certain chemicals reacting with manufacturers' rust preventative finishes, it is best to go with lubricants specifically designed to be used on locks. The best lubricants will provide protection while dry. That way, they will not attract or hold dust and debris that may interfere with the operation of the lock. Some of the better lock lubricants include Houdini, Lock Saver, and Tri-Flow.
To lubricate a lock cylinder, use an aerosol lock lubricant with a straw. Spray a small amount of lubricant into the cylinder. Take a key and insert and remove the key, wiping any dirt, dust, or debris from the key. Repeat this until the key appears to come out clean. The same cleaning procedure can be used on home, business, and automotive locks. Because of the increasing integration of electronics into automotive locking systems, a dielectric lubricant like Houdini should be used. That simply means it will not conduct electricity.
To lubricate the other internal parts of a residential or commercial lock, you will need to at least partially disassemble the lock. Removing the interior trim will usually allow access to the lock's moving parts, latches, and bolts as well. For larger bearing surfaces and other door hardware, such as hinges and exit hardware, lithium grease may be the preferred lubricant. Lithium grease is also available as an aerosol spray.
The best practice is to lubricate at least the lock cylinders twice a year. At the very least, care for your locks prior to winter's freezing weather.