Find a product
You can find lock-lubricating products such as graphite powders or Teflon-containing sprays at retail hardware stores both large and small. If you’re not sure of what product you should purchase, call a highly rated local locksmith and ask for their advice.
Some locksmiths advise against using all-purpose lubricants like WD-40 because they can eventually evaporate into a residue that attracts more dirt and grime.
Keep locks from sticking with simple, routine maintenance.
Spray it in
Whether it’s a dry powder or liquid-based product, always follow the label instructions and warnings.
Most products will direct you to place a nozzle or tube into the keyhole and spray the product, getting as much into the interior lock mechanism as possible.
You’ll probably want to have a cleaning rag or paper towel handy to clean up any overspray or runoff that may occur on either side of the door knob.
Give it a whirl
Make sure the door is open and you don’t lock yourself out.
If the lock is in a door handle, turn the handle back and forth several times and flip the interior lock several times, locking and unlocking the door.
Do the same with a dead bolt-only lock.
This will make sure the lubricant reaches all the moving parts within the lock.
Clean it up
Clean up any over-spray or runoff from spraying the lock lubricant, including wiping down the exterior of the door knob or dead bolt itself.
To keep your lock or door handle maintained, clean it as necessary or at least once a year.