Date:         Wed, 13 Dec 1995 09:54:08 CST6CDT
Sender:       Vanagon Mailing List <vanagon@vanagon.com>
From:         "Dan Houg" <fairwind@northernnet.com>
Subject:      propylene glycol washer fluid

there is a new washer fluid being marketed by Prestone that is a mix 
of propylene glycol, methanol, and water.  it is designed to prevent 
the washer fluid from freezing on the winshield at very low temps.  
i've used some and here's my impression:

it does indeed work at lower temps.  while the 'blue' methanol-only 
based stuff freezes into a blue smear at say, 0F, this stuff stays 
liquid.  it is particularly good at removing a real thin layer of 
frost, the kind that is almost too thin for a scraper to effectively 
remove.  the down side is that it leaves a little bit of a glycol 
smear on the glass.  it is also expensive.  about $3 a gallon.

i will use it for winter only, due to cost. it is probably worth it
if you don't park your vehicle inside for the frost removal aspect
alone.   you warmer clime people can stick with the blue stuff.

at cold temps, say below 0F, it is neat to watch as it 
fractionates into its various components on the windshield; the water 
freezes after the alcohol evaporates leaving a glycol 'wet' spot on 
the glass.  the ice then sublimes into vapor.  quite a little 
phase-change physics show from a little squirt of washer fluid... you 
probably don't need to comment on the dynamics of the phase-changes 
to your passengers.  they may already think you're strange and you 
don't need to confirm it.

-dan