Date: Fri, 10 May 2002 20:31:26 -0500
Reply-To: Joel Walker <jwalker17@EARTHLINK.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Joel Walker <jwalker17@EARTHLINK.NET>
Organization: not likely
Subject: some stuff about coolant
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from the June 2002 issue of Car and Driver.
Patrick Bedard
Top it up with green? Or orange? Which antifreeze?
It's 2002. Do you know where your corrosion inhibitors are?
Some folks take the yawn approach to what goes on between
consenting chemicals in the steamy privacy of a car's cooling
system. Not me. And now my sensitivities have been further
heightened. It was the weighty check I wrote to a welder for
filling in some missing places in a cylinder head that did it.
Funny how much aluminum went AWOL in the 30-some years since
that engine left the factory, enough to leave gaskets hanging
in midair.
Funny? I laughed all the way to the Coolant College. David
Turcotte is the technical director for Zerex, the line of
coolant products from Valvoline. He's a good-natured guy with
"Dr." in front of his name. That means he knows everything.
So I pestered him until he sent me a package of tech papers
about antifreeze and agreed to hold still for follow-up
questions.
Modern antifreeze, he says, is 96-percent ethylene glycol,
which provides the freeze protection, and four-percent
additives. When you dilute that blend 50-50 with water,
as the makers intend, you push down the freeze point to
minus 34 degrees Fahrenheit. In normal circumstances,
you also gain corrosion resistance ... for a while. The
freeze protection is permanent, but the additives are
consumed in battle, so to speak.
About half the additive is made of buffers to control acid
buildup; the other half is corrosion inhibitors to protect
metals.
Perhaps the battle is already going badly in your car.
A sticking thermostat can be an early indicator. The next
stage: As detritus <loose material that results directly from
disentigration> migrates through the system, it settles
in the most confined spaces. If your heater blows cold,
uh-oh.
I was hoping that technology, as it marches relentlessly
toward obsoleting everything I own, might also have
created new antifreeze formulas that would bring forbearance
and frustration to the chemcials frolicking under my aging
radiator caps.
Of course, no doctor writes the prescription before he
considers the patient. The "old" antifreeze technology
started in the '60s, improved in the '70s, Turcotte says,
and was superseded in cars of the '90s by two new
technologies. It turns out that an antifreeze transplant
into older cars will work fine with one of the new types;
the other will probably kill the patient.
The old technology, a.k.a. "conventional" a.k.a. "inorganic",
is green in color. Most of what you see on the shelves at
Wal-Mart and Autozone is conventional, including the yellow
bottles of Prestone and the white bottles of Zerex.
One of the new types is "organic acid technology," or OAT.
It's orange. General Motors pioneered this chemistry
starting with 1996 models in the U.S. and using the name
Dex-Cool. Ford changed a few models to OAT, then backed
away from it. VW, Audi, and Porsche are OAT users, too,
but most others have resisted.
Instead of OAT, most new cars now use a "hybrid" antifreeze
that's formulated with both OAT and the silicate
inhibitors from green (Japanese hybrids have different
inhibitors). It comes in too many colors to pretend this
type is color-coded. Interestingly, Turcotte says that
as the materials improve for the white plastic overflow
bottles of new cars, and they become less yellowing over
time, automakers are becoming more venturesome in choosing
coolant colors.
The promise of OAT is long-life corrosion protection, on
the order of six years/100,000 miles for the initial fill
instead of the two years/50,000 miles that was typical
with the old green stuff. The GM Dex-Cool formula works
fine in systems designed for it. But it eats old-style
radiators with lead solder, and the inhibitors work too
slowly to protect against the sort of corrosion that
happens so fast it actually erodes metal ... for example,
the cavitation likely in the imperfectly designed water
pumps of older cars.
"Cars born with green coolant shouldn't be changed to orange,"
Turcotte advises. It's also a bad idea to mix the two,
although the result doesn't immediately turn into witches'
brew.
Coolant technology is driven by the makers of new cars to
solve new-car problems (same with motor oil). By the time
a car gets old enough to be interesting to a collector,
the latest antifreeze blends have moved on to protecting
newer alloys and gasket materials. Fortunately, the
aftermarket lives by catering to older cars.
As for those aging characters we're keeping around as
playmates, no matter what antifreeze we choose, and no
matter how often we replace it, Turcotte says the best
medicine is to play often. Coolant down in narrow
crevices can become isolate, then overwhelmed by
corrosion. Once it starts, the best you can hope for
is a stalemate. You can't undo corrosion. To keep
protection active in all the crannies, the system needs
to be heated and circulated every 30 days, he advises.
Obvious question: What about the water we mix in?
He says modern coolants are designed to work with
"reasonable" levels of hardness and chlorides in tap
water. But magnesium and calcium, the hardness ions,
unquestionably contribute to scale and deposits,
which hurt cooling efficiency. And chlorides are
corrosive. He says distilled water gets rid of all
the worries. (It was 58 cents a gallon at my local
Wal-Mart yesterday). Or you can buy "predilute"
coolant already mixed and ready to go.
In my vision of purgatory, I'll be sentenced to
changing antifreeze in all my cars, day after day,
and some archangel with white gloves and a test
tube will be checking the color of my flush water
for contaminates. I have to keep flushing until
he can't tell the drain-out from the distilled he
carries in another tube as the control.
Here in this life, I've always changed my coolant.
I'm one of those guys who angonizes over details.
So the job takes a full afternoon for each car.
I drain everything that comes out through the cocks,
then top up with clear water, warm the engine, and
run the heater to circulate fully, then drain again.
Repeat at least three times.
What to do with the drainings? I called the local
pollution controllers. Antifreeze? Their book
had no mention of it. After thinking a bit,
however, they told me to put it out back in buckets
and let it evaporate. Rocks evaporate at about the
same speed.
Old coolant "hanging up" in the system is a real
concern, Turcotte says. But he also knows that
nobody gets it all out.
"We've done tests," Turcotte says. "If you open
a drain cock or drop a bottom hose, you might get
50 to 60 percent out. The best machines, the new
ones going into Valvoline quick-oil-change shops,
get 80 to 85 percent." This is a manageable level
of contamination, as long as the new antifreeze
doesn't fight with the old.
Next month:
The doctor writes a few prescriptions.