I used Vaseline when I put my tank back several years ago.  No problems
with it.

I suppose one could also go to a hobby shop and get some of the rubber
lube that's intended to lube the rubber bands in rubber powered flying
models.  That stuff is definitely rubber friendly.

Mike

Jake de Villiers wrote:
> I use rubber grease for things like that. Comes in a squeeze tube and lasts
> so long I don't remember where I got it!