On Sunday, May 27, 2012 1:21:53 PM UTC-5, Tegger wrote:
>
> You appear to be in MN. What's the coldest it gets for you in the winter?
>
> Call a locksmith. They have special oils that are meant for this purpose.
>
> If you can't locate a locksmith, go to a hardware store, gun shop, or
> sewing machine shop, and get a small container of the very lightest,
> thinnest oil they have. If it's aerosol, the better for you.
>
> Spray or inject this light oil into the lock. Do not skimp. If not an
> aerosol, drench the lock in the oil and work the key in and out of the lock
> a few times to drive the oil deep into the lock.
>
> Also, use a NEW key, and not a new one made from the old one; worn keys
> will cause big problems, especially with worn locks.
>
> Do NOT use dry graphite as a lock lubricant.
>
It's been as cold as -30 degrees here. However, I find it hard to believe that the problem with the driver's side door lock is weather-related given that I had no problems until a few days ago.

What kind of oil do I need? How do I know that this wouldn't make the problem worse? (You said that graphite would make the problem worse.)

If the light oil works, is it a permanent fix, or do I still need to have the tumblers or other lock mechanism fixed/replaced? Would it be a good idea to treat the door lock on the passenger's side as preventative maintenance? Is there a chance that I could ever have a similar problem with the ignition? If that happens, I'd need to call for a tow truck.