Hey folks - As a GM dealer tech (Saturn/Chevrolet) for the last 6 years, my
experience with dexcool is thus:
  It fails. Early,often. It gums up heater cores and radiators. Lasts nowhere
near 100k as advertised, usually it goes away around 20-25k miles. It gets
floaters in it and turns a sick brownish color.
  GM has issued a couple of TSBs on this, saying the fix was to replace the
dexcool with more dexcool after a thorough flush.
   According to GM, dexcool should never be used in cooling systems
containing any soldered joints (I.E. brass radiators or heater cores) because
the organic acid base attacks the soldered joints.  This to me says
"underdeveloped product" .
    I, personally, would never use dexcool in anything, as i have never seen
it last over 45,000 miles, ever, in any application. I have seen an average
of 6 cars a day five days a week for 6 years.....
   Just my 2 cents, and YMMV. - Ed