Tom, I believe you're referring to a product called Penetrol, manufactured
by Flood Company. Here's an excerpt from an answer to a query that I made to
the Flood Company about Penetrol back in 2002:
~~~~~~~~~~~~

<me> I hear good things about Penetrol for restoring lightly-oxidized
fiberglass surfaces. Is Penetrol the same product as the Marine Penetrol I
see at some retailers? If they aren't the same, how are they different and
which is better for this use? </me>
<Flood> Yes, Marine Penetrol and Penetrol are the same product. We no longer
manufacture Marine Penetrol labels. We recommend cleaning with Dekswood
Cleaner (1:2 ratio) and allow the fiberglass to dry 24-48 hours. Saturate a
clean rag with Penetrol. Apply what you can in 5 minutes to a small
designated area. Wait no longer than 5 minutes and wipe off the excess with
a clean, soft cloth. Gentle buffing will increase the luster. Thank you for
considering Flood products.
Tech Services </Flood>
~~~~~~~~~~~~

For a slightly faded but otherwise unscathed top, I can vouch for it. I
little goes a long way. I bought it at Home Depot or the like. -Phil

On Wed, Nov 5, 2008 at 9:59 AM, John Meeks <vanagon@gmail.com> wrote:

> Tom,
>
> Was it Interlux Pre-Kote primer and Premium Yacht paint? Scott Wetzel
> had good luck with that combo as seen here:
> http://www.vanagonauts.com/Roof---Maintainence,-Painting135.htm
>
> John Meeks
> '91 Multivan, '85 GL bits
> Northern Michigan
>
> Vanagon Rescue Squad
> http://www.vanagonauts.com/Vanagon_Rescue_Squad74.htm
>
> Radio Call:KC8ZFN
>
>
>
> On Mon, Nov 3, 2008 at 11:51 AM, Tom LaLanne <tomlalanne@sbcglobal.net>
> wrote:
> > Hi folks,
> >
> > When I first bought my '86 Westy in 2001, its tan top wasn't pretty.  In
> addition to rust stains from the original hardware, its finish was dull and
> milky.  I spent a lot of time cleaning the rust and polishing the
> fiberglass, and replacing all the bolts and other hardware with stainless,
> and then applied a good auto wax over the top.  The top looked beautiful,
> but it had been a huge amount of work.  Several years later, the top had
> begun to fade, and I read on the list about someone who recommended painting
> the top with a product whose name I cannot now recall.  The product's main
> purpose was as an additive to paints to make the paint spread evenly.  I
> bought a can at a marine outfitter - I think West Marine.  After washing the
> top, I painted it with this stuff.  It was incredible.  The top looked
> better than after I had done all the work several years before.  Somehow, I
> felt almost like I was cheating.  Well, I'd like to cheat again, but can't
> remember how.  One of those dreaded senior moments.  Does anyone know the
> name of this product?  I've tried unsuccessfully to find it in the archives.
> >
> > Tom LaLanne
> >
>