Tim, the van I have was always serviced at the dealer until I got it only a
couple of years ago.  The head pitting, and gasket problems I experienced
were long term problems and had probably been going on for about the past 5
years at least.  So since the van only had dealer coolant in it before that,
and I only added Wal-Mart coolant as needed, I really don't think it played a
part in the destruction of the heads.

However, I think that the point that has been stressed here on this list is
that flushing your coolant system every couple of years (no matter what
coolant you use) is the way to go.  I agree with this.  My coolant system had
never been flushed and I was putting it off for just a few months longer
until I could put a rebuilt engine in (wouldn't have helped the rampant
pitting anyway).  If my coolant system had been flushed every couple of years
by the dealer or by the owner then I might not have had as much pitting or
any for that matter.  The coolant was brown when it came out!

So my opinion is still go with the cheapest Phophate free stuff you can find
(Wal-Mart, etc) and just do the flush every couple of years and you will be
fine.  If you want to pay more for the blue stuff and you sleep better at
night because of it, then that's great too.  A good nights sleep is worth an
extra $20-$30 every couple of years any day :)

Thanks,
Ken Wilford
http://www.vanagain.com
John 3:16
Phone: (856)-765-1583
Shop:   (856)-327-0027
Fax:     (856)-327-2242