OK, i'm gonna totally nerd-out here(from my engineering background), but I think it could be for an electrical part, possibly RC.
In the electronics world, we use "FET's" or "field-effect transistor's" in lots of boards. They get really hot, and these greases help conduct heat away from the part....
OK, I will go back to my cave now, and play a video game, and imagine I had a girlfriend too....