There's two things that our chains need. First is to keep them lubricated with SOMETHING. I won't even begin to suggest what you should use since we don't need another 10 page thread of options and bickering....

The second issue is to keep the chain cleaned of grit. This is just as important as keeping the chain oiled or greased since having grit in it can wear it out at least as fast as not being lubricated. It doesn't matter a hoot what the outside is like. If the links are beginning to feel the least bit gritty when flexed and rotated then you should deep clean it first before re-lubing.