I'm with tbone, Dow 111 is the way to go. It's been the standard for many many years and only fell out of favor when nitrox became popular and with no good reason, 111 is fine at lower O2 levels. The other lubes are bad for separating and drying out, I have taken very old regs apart that had 111 in them (or at least a similar silicone lube) and the lube was still in perfect shape. Per the msds sheet, it is non toxic except at high temperatures and when mixed with some pretty bad stuff...which you would never have around a reg anyway.