I do not know what type of o-rings that Robart uses.
Why does that matter?
Different types of o-rings will react with various lubricants. If using the wrong lube, your o-rings could swell and/or harden or crack; that goes for your tubing as well. It does not take long to ruin an o-ring.
I have found through the years that silicon grease or food grade silicon spray are about the safest to use, except on silicon and natural rubber o-rings.
Follow the link to a compatibilty chart by Marco Rubber http://www.marcorubber.com/compatibility.htm

Pure silicon grease is available through a local Dive shop or on-line.
Food grade spray is available through your local NAPA shop or on-line.