if it is the bolt used to drain out old mobile / engine oil, then chill,
no big problem. my car had the same problem of leaking oil from the same place.
the mechanic did bore that hole again with a bit bigger number
with a tool called mosses, spellings??, that makes grooves 'churian'
inside the hole.
then the bolt matching new number with washer would do the rest.
'did charge rs.50/= back in may, 2007, other was demanding rs. 200/= at the same time.
no problems since then.
when done, please do update us.