Some more thinking...the curve is based on "pure" ethylene glycol, but the stuff we buy may already have some water in it, thus achieving the optimum ratio when mixed 50/50.� I guess I'll stick with what the VW engineers have already calculated.� And that is:� 50% coolant, 50% water.� Now, for the debate on distilled water versus tap water...distilled must be better, but tap water is sure easier.� And, for the record, I change mine every 2 years like the book says, and no head gasket leaks after 180,000 miles (although with a recent broken water pump belt and overheating, I may have entered into the danger zone).

Rich
San Diego (STILL not freezing in these here parts)

--- On Wed, 12/2/09, Richard Koerner <rjkinpb@SBCGLOBAL.NET> wrote:

From: Richard Koerner <rjkinpb@SBCGLOBAL.NET>
Subject: Re: weak coolant - winter's approaching!
To: vanagon@GERRY.VANAGON.COM
Date: Wednesday, December 2, 2009, 7:43 PM

From the curve, looks like a 60% antifreeze and 40% water mixture is significantly better than a 50/50 mix....wonder why we all do 50/50?� Corrosion protection should also be better with more antifreeze...just thinking.

Rich
San Diego� (doesn't freeze here, that's for sure)

--- On Wed, 12/2/09, pdooley <psdooley@VERIZON.NET> wrote:

From: pdooley <psdooley@VERIZON.NET>
Subject: Re: weak coolant - winter's approaching!
To: vanagon@GERRY.VANAGON.COM
Date: Wednesday, December 2, 2009, 7:17 PM

I guess you didn't read the article.

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
Michael Snow
Sent: Wednesday, December 02, 2009 9:44 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: weak coolant - winter's approaching!

On Wed, Dec 2, 2009 at 6:38 PM, Mark <mbrush@gmail.com> wrote:
> So here's a question - maybe an easy one... So I'm in the middle of a
> flush-n-fill with ye olde bus. �I've probably got something like 70%
> distilled water and 30% coolant in there at the moment (given that it's
hard
> to flush ALL the coolant out). �I can't drain and refill with a 50/50 mix
> until the weekend. �But I live in Michigan and it's getting COLD!
�Supposed
> to get down to 20 degrees F on Friday morning. �Am I doomed? �Will the
> water/coolant in the van freeze and cause damage? Or will it just get
slushy
> and I'll be o.k. until Saturday? �I tested the coolant and the floaty
balls
> tell me I'm good until 20 degrees F.
>
> I found this info and chart from the Alaska Science Forum to be kind of
> neat. �Apparently, higher coolant mixes don't necessarily mean better
> protection:
>
> http://www.gi.alaska.edu/ScienceForum/ASF6/680.html
>
> thanks for you thoughts!
>
> --
> Mark
> 1990 Westy (2.1 - manual)
>

Coolant is cheap.� Engines are expensive.� Drain some of your mix and
add pure coolant until you are satisfied with the protection level.

-- 
Michael Snow
1987 Syncro TiiCo
1982 Westfalia 1.9TD
http://slowmachine82.blogspot.com/