You shouldn't lose any of it into the lifter valley, there is a top and bottom part of the valley pan with a couple of vents to pull crankcase gases through at the bottom. They do tend to dry out and crumble when they get old(real old), warm up the motor and let the rubber soften and then use some needle nose pliers to remove it. You should be ok...just order a new one first, I've found alot of places don't keep them in stock anymore.