Five years ago, I wired the house with generic HD 16 ga transparent speaker wire. I haven't had any use for it until now. I will finally install sound speakers for our HT system. When I pulled the wires out of the wall, I noticed they had oxidized because of the greenish color. What I also noticed was that this greenish color also appeared along the entire length of the speaker wire. I'm sort of puzzled because I thought oxidation would occur only at the ends of the wire where they were exposed to the air and not along the entire length where it is insulated. Since the entire run of wires are already oxidizing, do I need to replace all of my speaker wires with Oxygen Free type of wires? My runs are relatively long, 30+. In addition, I had also run some wires to the garage, back yard patio, and bedrooms so, replacing them all may become an expensive nightmare. I checked them all and they all had the same problem. Thanks for the help.