> " Distilled or deionized water is very aggressive Water "wants" to
 > contain minerals and distilled water will attack cast iron and aluminum far
 > more aggressively than mildly hard tap water. "

I have to completely disagree with this so called 'theory' about distilled
water. I spent 20 years in the US Navy as a Submarine Reactor Operator and
I can tell you that it just doesn't stand up to scrutiny. The makeup water
that is added to a reactor plant, whether it is a Navy plant or a civilian
plant, is 99.99% pure water and is stored in stainless steel tanks. All of
the piping to add the water to the system is stainless steel along with the
pumps used to add it. One of the reasons for the selection of stainless
steel for the tanks, piping, and other equipment is precisely because it
doesn't corrode in the presence of water at the temperatures that the
coolant is operated at without the presence of oxygen, sodium chloride
(salt), or a pH that is too low (acidic) or too high (alkaline).

Doing a search on Google for "stainless steel corrosion pH water" will
yield more than enough information to make your brain hurt on this subject.

Just my 2 cents. I'll get down off the soap box/lectern now and let you
resume your normal programming.

Greg Irick
Silverdale, WA
gregi@vwtype3.org

'65 Notchback with a Britax sliding rag top
'80 Westy
'00 Jetta VR6