Ever had to try and unlock a car when the door locks are frozen shut? If you need to park outside and you live in a cold climate, this can be an everyday problem! Here is a super inexpensive fix.
First, buy a round magnet, about the size of a quarter. You can find these at your local craft store, or you can remove one from a fridge magnet you no longer like. Then simply keep the magnet over top of the door lock. This will prevent moisture from entering the lock and freezing, which is what causes frozen door locks.
If you are worried you will forget to put the magnet on, simply leave it on all the time. If you are worried about it looking funny, simply paint or spray paint the magnet with silver paint, and it will blend right into the door lock.