I was just doing some car & motorcycle tinkering in the garage this afternoon (stormy outside - I have a heated garage) and while I was using PB Blaster on one of the bike's exhaust nuts, I happen to sit and read on the can while I was letting the exhaust soak in the PB. (I was board so I read it)
It actually recommends using PB on hard toilet flappers, and I think it mentioned o-rings. So sounds like a candidate for rubber stuff, that's auto rubber that is. I might later give the PB a few shots on some cracked grommets I have on one of the bikes that are a little on the hard side.
