There's a thread on SS somewhere that has a huge debate over this, I changed to DOT3 because I drive my truck fairly regularly, while the military ones may set for months on end. Also water absorbs into DOT 3, it seperates from DOT 5, for some reason everybody thinks this is good, but the water then rests on the bottom of your brake lines, I had a spark from a arc welder hit the bottom of my brake line in a low spot and that's all it took to start a leak. With the water suspended in the DOT 3 it can't rust anything effectively (as quickly) as just the plain water concentrated at the lowest spot in your brake lines. OF course, YES, for that reason you should change your DOT 3 every two to 3 years, depending on how humid it is where you live. But thats why I went back to DOT 3. because this site, and my experience with my leak caused me to decide DOT 5 isn't right for me and my Deuce.....YMMV.