I really don't know much, but I have heard to be careful using anything that is oil based, as the dash can dry out and crack.  My brother, who details cars, says to be sure and use silicon based products on the dash.  I do know silicone is bad around painted areas though, if you ever want to paint your vehicle in the future!  I would be interested in hearing what is recommended by you guys that keep your vans in top condition!  

Julianna
1991 VW Vanagon Westfalia (Ophelia)
1990 VW Vanagon Westfalia (The Rastafalia) Now Parts :(
1988 VW Vanagon Tintop (James)
1985 VW Vanagon Weekender Westfalia Automatic Transmission (Texas 2) *For Sale*