Tires: tire mounting, tire bead, time jim

Question
I had a junkyard mount a tire for me and when I got home I noticed that they had used old black grease on the tire bead for sealant. Will this be OK or might it harm the tire bead over time ?

Answer
Jim,

It depends on what the grease was.  Some tire mounting lubes look like regular old black grease.

But if it isn't, the bead will aborb the oil in the grease and become soft and eventually cause a leak.

But I would question whether a junkyard would have proper tire mounting lube.  

So it could be either way.