I ran into this some last year. Here's the parts of this that I do know....
UP valves and cylinders are greased for lifetime with a Dow Corning lubricant

[link]http://www.up-1.com/dow.html[/link]

I didn't know that at the time, but should have thought more about it. So, trying to be proactive, put the BVM lube in liberally on new gear, and slowly started to have some issues, and called UP directly, and got the story last year about they don't recommend the o-ring lube. It can ever so slightly, increase the o-ring's size, thus helping it to seal if it's got trouble.

But, his remarks were that given the duty cycles that most of our gear see's it should not ever be nesessary. In industry, o-ring / cylinder setups, they should be able to have 10's of thousands of cycles to them.

I think Tom, from JMP also uses this same, lifetime grease on his gear as well.

Any other brand, I don't have any idea what lubricant they could be made with or not. Perhaps other brands the O-ring lube helps.

Totally asside from the question of swelling the o-ring, I kind of came away from it, visualizing it like if you've got a heavy grease on something and you put a thin oil or a WD-40 weight on it, it could actually, 'wash away' the heavier grease.

Lance