Doug, you mean to say you've never heard of someone riding their bakes a little too much going down a mountain and heated them up so much it cause the water in the brake fluid to boil which made the brakes useless? I've heard those stories for years. Around where I live with heavy dew the normal every morning thing, my brake fluid turns dark as it absorbs moisture pretty rapidly. I should change it yearly but I'm not that good at keeping up with it and I don't have any trips over the mountains planned - plus I come down mountains as slow as I go up them. Yes, brake fluid has an affinity for moisture and fluid reservoirs are not air tight so there's no way to prevent it from becoming contaminated unless you move to a very low humidity area in the dessert.