Hi all. I tried searching for this topic but didn't see anything. Wondering if anyone can help? I'm a new owner of a Jeep JK, '07. I don't have power windows or locks. While that's not an issue, the issue IS that I can't manually lock or unlock the doors (both driver and passenger) from the outside with my key. The cylinders don't turn at all. The previous owner said to just put some "white grease"? on/in the cylinder and it should loosen it up. Any truth to this? What's "white grease"? Is there a different method I should try? Thanks.