csnow,

Whether distilled water is more reactive near it's boiling point than tap water is a question for chemists. But, my old english mechanic mentor once told me not to use distilled water in the radiator.
I never have nor have I ever had to replace any cooling system components in any car except my 300E. It was leaking a little around the water pump and then broke it's neck at the top of the radiator, both well known problems with this model.

This level of care is interesting since my new V8's seem to run hotter than other engines I've owned. I'll watch to see what the majority opinion is on "water" Sparkletts or Arrowhead

__________________
Ed "Don't Benz's just feel better..."

Current wives...
2000 ML430 Skyview "The Mel"
2000 CLK430 Cab "The Cab"
85 300D Turbo "The Diesel"

Past wives...
92 300E
85 190E

"One should as a rule respect public opinion in so far as is necessary to
avoid starvation and to keep out of prison, but anything that goes beyond
this is voluntary submission to an unnecessary tyranny, and is likely to
interfere with happiness in all kinds of ways."
Bertrand Russell