One small note,
Plus, when the anti-freeze breaks down over time, can and does
sometime become electrolytic... Really, really messes with temp
sensors and ECUs.....
Michael aka ECHO
--- Joel Walker <jwalker17@earthlink.net> wrote:
> > Anecdotally, I've been told that certain coolant mixtures
> become
> acidic after
> > a year and should be changed annually.
> > Sounds like a good geeneric question for the list.
>
> what i've learned from noising around and reading and talking
> to the
> tech folks is this:
>
> antifreeze contains additives, just like motor oil contains
> additives.
> and just like motor oil, those additives get used up ...
> become
> depleted over time. some of the additives in antifreeze
> prevent
> corrosion. some of them lubricate the water pump. in about
> three years
> or 45,000-50,000 miles, those additives are just about used
> up. the
> tech folks at BASF (the folks who make the vw blue
> phosphate-free
> antifreeze. which is, according to them, the same stuff as the
> mercedes, porsche, toyota, audi, volvo, and saab antifreeze
> ... just
> different colors for each brand) tell me that the coolant
> NEEDS to be
> replaced every two years, to replenish those additives.
>
> don't believe it? ok, go check on the 18-wheeler trucks. it
> seems they
> have the same problem, different solution: they have a filter
> on the
> coolant system. and on each side of the filter is a valve that
> they
> can shut off (so as to not lose much coolant when they remove
> the
> filter). the filter turns out to be sort of hollow, and in the
> hollow
> space, they put chemical additive sticks. so they can shut off
> the
> truck, turn the valves, yank the filter and put a new filter
> with new
> chemical additive sticks back on the truck, turn the valves
> again, and
> be back on the road in about 30 minutes. they don't have to
> wait for
> the truck to cool overnight like we do. why such a system?
> cause their
> antifreezes are 'guaranteed for 150,000 miles!" ... which is
> like six
> months of driving. and to wait eight hours for the coolant
> system to
> cool down before draining it costs them lots of money.
>
> the point being that coolant, like any other fluid on an
> automobile or
> truck, NEEDS to be replaced. regularly.
>
> the BASF folks also said that the phosphate-free requirement
> was only
> for areas that had hard/high-mineral-content water. with that
> type of
> water, there tend to be precipitates or deposits formed in the
> cooling
> system. possibly in the radiator, but certainly in the bottoms
> of the
> two plastic coolant tanks. at the very least, it 'looks bad'
> (according to BASF). they said any ethylene glycol antifreeze
> would
> work fine, IF you replaced it every two years.  they were not
> very
> flattering of propylene glycol (possibly since i don't think
> they make
> an antifreeze with it), saying that it didn't handle the
> ranges of
> temperatures that ethylene glycol did. someone on the list
> said this
> wasn't true, but that less of the e.glycol was required (than
> the
> p.glycol) to reach those same extremes.
>
> as i understand it, the coolant consists of antifreeze and
> water for a
> reason:
> - the water carries the heat away from the metal parts. water
> is
> better at this job than anything else they've come up with
> (that can
> be found cheaply and in most areas. i kinda doubt that any of
> us want
> to be riding around on top of a liquid sodium metal cooling
> system,
> like some of the early nuclear reactors).
>
> but water freezes. and boils. so they add the antifreeze to
> lower the
> freezing point. it also raises the boiling point, and the
> engine
> becomes useful in most climates. a 50-50 (water to antifreeze)
> mix is
> considered normal. if your temperatures are extreme, either
> cold or
> hot, then the mix can be adjusted to 40-60 or even 30-70, but
> 30-70 is
> the most extreme case i've heard of in an automobile used for
> general
> purposes, in most places where humans live in cities.
>
> the problem with all this is that you mix hot metal and water
> and you
> get rust. so something has to be added to prevent that rust
> ... and
> that's where the additives come in. once the additives are
> depleted,
> there's nothing to prevent the hot metal and water from
> forming rust.
>
> unca joel

=====
MY first VW!
1980 Vanagon L "D'Arius"
LOOK a picture!!!http://www.geocities.com/echo207/vanagon.html
Need any general computer help? Computer blonde? E-mail:
echo207@excite.com and I will see what I can do to help.
And a limping 84 buick Skylark

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