) 

>  > While rotating the tires on the '85, I found this metal thing in the bag
>  > with the jack.  It is marked "10" at one end "13" at the other.  Is this a
>  > wrench?  Or is it some kind of magic de-tighten und unloosen device from
>  > VW-GMbH?
> 

It's actually a special tool you need to use to activate the round 
silver metal thing that's located on the dashboard of the Vanagons.