NOBODY, not even vw dealers were able to find a paint code/name for the
"greenish" silver paint used on the fiberglass bumpers of vanagons from
'87-'89 (wolfsburgs, etc).
anyway, after much research, and the help of a local auto paint supply place,
i have come up with the official vw name/color code for the '87-'89
fiberglass bumpers.
the VW color name is: "Jade Metallic" and the VW color code is: LN6V.  

for those of you who use DuPont, the corresponding DuPont color code is: H8607

this being said, you call call your local VW dealer and order the "Jade
Metallic" LN6V in little touch up tubes, or spray cans to touch up
scuffs/scratches/fixit yourself jobs on your '87-'89 silver painted
fiberglass bumpers.

Note:  Jade Metallic is NOT the color used on the '90-'91 silver bumpers,
that is a different color, a more greyish silver, without the green tint like
was used on the 87-'89 ones.  i have yet to research that.    hope this helps
someone..
chris