Care for your waterproof end caps

I'm doing some prep work on my lights for my tank and that includes a good cleaning of everything.  In that cleaning, I noticed that there's two rubber rings on each of these caps; one really thin one that goes between the end that has the actual bulb conductors in it and the tube that supports the bulb, and a second one that attaches to the bulb support and an end cap that tightens the ring around the glass of the bulb.  Now these are VHO end caps; I'm not sure if T5's are the same.  So to my questions
1) Is it advisable to put anything on these threads to keep them easy to move - like a trace amount of vaseline or something?
2) What, if anything, do you put on the rubber rings to keep them soft, pliable and keep them protecting the conductive parts of the bulb and socket?
I'm new to using these so I have no idea.  Thanks in advance.
--AJ