When i had my intake off the bottom of the plenum was full of oil. When i was painting it i tipped it on its side and a ton of oil poured all over my pants.
I didnt expect it and i wondered how much oil was actually in it.
When the intake manifold is sitting upright like mounted on the car its that bulb at the bottom i think fills up with oil.
You might tip yours up on its side and let it sit in a pan or something and see if yours has collected oil as well.
Some one mentioned though it could help collect dust if any gets in?
DX3?.. huh?.. well ZX3 = Zetec the 05-07 has a Duratec so D