It's interesting to note that even though there are a lot of O2-safe lubes on the market, meeting the same or very similar specs, and Krytox was, in the early days of tech diving, usually mentioned in the same breath as Christolube, that just about every reg manufacturer who specifies an O2-compatible grease, now specifies Christolube. Maybe they are all just parroting each other, but seeing as how the O2 lubes all cost roughly the same, and that one tube will last most divers a lifetime, I don't see any point in looking for alternatives to Christolube. Oh, one problem with Krytox is there are a heck of a lot of different grades of it, and I have never managed to get a clear recommendation of which one to use for scuba purposes - when I asked a Dupont rep a few years ago which, I was told "" 240 AC or 240 AD. Or maybe GPL 205 or 206. Or there are a couple others they use."
Re using silicone for <40%, it is also worth noting that most of the reg manufacturers that recommend using O2-compatible lubes recommend it not just for regs that will see high-FO2s, but across the board, on the grounds that it is simply a better all-around lube than the old silicone lubes. Scubapro, for example, says that regs serviced with it show more consistent I.P.s.
