I realize I'm late to this party but in NM most of us use a product on decks (most of which are redwood) called Australian Timber Oil. We're at 7500+ feet and between the wind, harsh sun, low temps, snow, ice, hail and low humidity in the spring and early summer, wood surfaces get a real beating. The good thing about it is it doesn't chip or flake or peel. It just loses its luster and water doesn't bead as much. But recoating is a breeze. You just clean off any dust, dirt, etc and brush it on. It contains both linseed oil and tung oil in it plus alkyds and coloring agents. Not cheap (a gallon is about $40), but it works very well. Clean up with mineral spirits and you can even use mineral spirits to thin it a bit (although they tell you not to). Up there we recoat exposed decks every 2 years, but as I already mentioned that is a very tough climate for wood finishes. This does work well on treated pine, however as somebody already mentioned the resin in that wood under that NM sun will have an effect on the stuff. Our lowest deck is treated pine...at the time we did it, redwood was just too costly. Good luck.
