I have an Army Survival book my grandfather gave me when I was a kid. Reading through it now (I'm almost 30) I stumbled upon the gun maintenance and hunting section.
Of course, the manual says that if stuck in any kind of survival situation yadda yadda yadda you'd be best poised to survive with the knowledge contained within the book and at LEAST a .22 rifle.
It went on to say that wood and steel, while durable, don't like extreme temperature changes. If the gun is used outside in extreme temperature, keep it there. Also, while some posters have said that a little oil is fine (and I'm sure they're right), it said that cold guns shoot best dry.