I think the concern with electrolysis and VW coolant is mainly to use no
phosphate antifreeze because that phosphate enhances the electrolysis
between the aluminum in the block and the rest of the iron, steel, etc etc
that the coolant comes into contact with. I don't think our antifreeze
'protects' the metals, it just doesn't have the stuff that can degrade the
metals as used in our fancy motors..
  This is "real stuff"...electrolysis.  Normal corrosion happens but when
you add some errant DC current to a good conductor like water with phosphate
in solution , and then run it over and through dissimilar metals...the
softer metal gets eaten!...
  If you have ever seen a motor thats been run for a long time with the
wrong coolant....not pretty..
  Distilled water has no minerals in it.  Better than tap or well water
which may also enhance electrolysis..No problem with pure water..
  Now, is it better to be able to run your engine at ~240f without boiling
or to have it run at <212f if possible?  Dunno, antifreeze is good for
street driven vehicles..especially during winter when freezing is more
likely or when you might forget (like I did) and cost yourself a bundle of
money by ruining a very  expensive motor..
  Don Hanson
On Sat, Dec 12, 2009 at 4:59 PM, Karl Wolz <wolzphoto@q.com> wrote:

> OK, now the question is:
>
> What about the electrolytic reaction between dissimilar metals?  My
> understanding is that one of the functions of antifreeze is to protect
> metals.
>
> Karl Wolz
>
> -----Original Message-----
> From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
> Rocket J Squirrel
> Sent: Saturday, December 12, 2009 3:26 PM
> To: vanagon@GERRY.VANAGON.COM
> Subject: Re: About coolant
>
> My son will be pleased to know that he's right.
>