Thanks, Mike.
The engineers never made this decision in the first place.  Engines and
their auxiliary
systems still use more or less the same types of metallurgy they always did.
Cast iron, aluminum, brass, lead solder, and occasionally some bits of 'pot'
metal or zinc castings.

The coolants and additive packages came about in a secondary manner.

I am sure you remember the really lousy aluminum-silicon castings made by GM
a number of years
ago.  Mercedes Benz still uses aluminum silicon technology, although the
development of the
metallurgy is much better now.

Companies like GM often adopt a proprietary system like Dex Cool.  It is
sometimes for marketing
reasons as much as for technical and reliability reasons.

My, perhaps blunt, comment was that it is not a big trick to flush out a
cooling system so that you can
put whatever you want back in it. And I stick with that.  You can get the
system as clean as you need it
to be.

And you can choose what you wish to put in it, but it is wise not to mix
systems if the formulator says
not to do so.

There have been so many complaints against DexCool that I would not feel
hesitant to replace it with
HOAT   technology or even the old green juice.

As I mentioned much earlier, we have purchased the packages which go into
Dex Cool, blended it with
glycols, and used them in commercial systems because the customer wanted the
environmental benefits
of the OAT.  In these systems, it was a somewhat inferior system, definitely
not a longer term or superior solution.

HOAT is reputedly better.

Apparently I stepped on the sensitivities of Woody, but I dont retreat very
much from what I have posted.