Does anyone know how to prevent locks on car doors from freezing, this is usually only a problem in older cars. I'm not thinking of solutions like WD-40 that really only work for a few days and then are needed again, I would like a more permanent solution if anyone knows of one.
Unfortunately I think this is simply a consequence of living in colder climates. The only long term solution to this problem would be to somehow seal off the locking cylinder from condensation and the elements, which would be nearly impossible to do if the only method of unlocking the door is by physically inserting and turning a key.
A word of advice for readers: do not use WD-40 in your locks. Over time the residue that dries inside the lock will build up and the locks will get even tighter.
Common solutions for lock de-icing include:
Do not try to pour warm or hot water over the lock -- the water will seep in and just freeze again and you'll just end up making the situation worse.
As preventative maintenance, there are lock lubrication products (e.g. Houdini Lock Lubricant) that can be applied before the cold season starts that may reduce the likelihood of a frozen lock.
Disclaimer: Any of the above methods may damage your paint over time, so please be careful to avoid contact with the body of your vehicle.