Woketman weplied ...
... Some materials will swell, some not. I know that Buna-N O-rings are perfectly compatible with Vaseline.
Vaseline, lube, grease ... ? Seems counterintuitive to put slippery stuff in the midst of a system that depends on friction to function. As I recall, [link=http://www.glennis.com/brake.htm]Glennis Aircraft[/link] brakes don't need grease to function properly or consistently.
Mike