I use the 3M Marine Fiberglass Restorer and Wax product available from Mest
Marine (
http://www.westmarine.com/webapp/wcs/stores/servlet/ProductDisplay?storeId=10001&langId=-1&catalogId=10001&productId=72505 )
on my Westy top. We own a boatbuilding business and use this product to
detail client boats after repair. If your top is highly oxidized (and it is
probably worse that you would think) then be prepared to spend a good day on
it. The product removes oxidation and leaves a shiny wax coating. Polishing
with a buffer helps make it go faster and shine better. In the summer months
I use a marine spray fiberglass spray wax on the top everytime I wash the
van to keep the oxidation away. I think the product is made by "Starbrite"
(3M makes one too) , but any marine fiberglass spray wax should do. One tip
to remember is to take the extra time to mask off the black rubber molding
all around the bottom of the top to prevent smearing black streaks into the
wax and all over your applicator. Also get alot of applicators because you
will need them on a highly oxidized top. They build up with the product and
crud quickly.

Happy waxing!

-Tracey
85 Westy
68 Campmobile
78 Transporter