For low temp lubrication either molycote or PTFE based lubricant should be OK for temperatures down to -73C

http://www.dowcorning.com/applicatio...t.aspx?R=387EN

I would say to use this stuff sparingly, As has been mentioned, the duty cycle of pneumatic systems on robots is particularly low, so in most cases I would say lubrication at service intervals is all you need.