Replacing the O-rings on my '76 308 distributor shafts. I did this years ago to stop the annoying oil leaking from the bottom of the distributors. Now they're leaking again. Apparently someone's been in there since I replaced the O-rings years ago. Today, when I took out the first distributor, I found someone had ran a bead of silicon around the O-ring then pushed it onto the shaft while the goop was still wet to form a sort of gasket. It hardened to soft rubbery texture. It's been years, but I don't remember putting silicon or goop on them. Is this a common practive that I don't know about? If so, what is the goop? Brand name or generic name of the goop? I don't see how goop would help seal on a rotating shaft? Puzzled?