That grey stuff---You don't have a quart of oil in the trunk
do you? I had a quart of oil in the trunk of my old ZR once
and it opened up and spilled all over, it wasn't pretty and man
did I feel stuuuupid.

h34r: The residue started coming out
from the seat and it was greyish in color--most likely not your
problem but if it is easy fix!