I've looked at a lot of threads that discuss how much, and when to apply silicon to the o-ring. Everyone seems to agree on not opening the housing after each dive, or every day after diving, unless strictly necessary (replace the battery, memory card, sandy environment). I've followed that advice since day one. However, it seems like, at this rate, the amount of silicon I have stocked will last longer than my lifetime. I have six sealed S&S o-ring-silicon kits, and so far in three years, I haven't gone through the first one. Does silicon turn bad? Is there a shelve-life? It's stored in my Pelican case with the rest of my gear, in my basement, so humidity and temperature shouldn't be a problem. Any advice?