Redline Water Wetter

Fisher, Scott Scott_Fisher at
Fri Jun 8 10:41:20 EDT 2001

Oliver Llenado asks:

> has anyone used Redline Water Wetter?, 

I use it in all cars *except* my Audis.  I'll explain more below (boy,
*will* I...).

> can i mix it with my coolant? or 
> do i have to flush my old coolant?.

You should replace your coolant every N years (where N varies with the
engine and/or coolant manufacturer).  RedLine Water Wetter (henceforth RLWW)
will be most effective in a new coolant mix; it may be a waste of money
adding it to old coolant that is already at the end of its useful service
life.  And while it's in both of my non-Audi vehicles at the moment, it's
not in either of my Audis because I'm not convinced it isn't a waste of
money in an Audi with NEW coolant.

Here's the thing: RLWW doesn't fix problems in your cooling system -- it
does reduce your car's operating temperature if everything else is working
correctly.  The theory behind its operation is that it's a simple surfactant
or detergent, which reduces the sizes of bubbles that form from localized
boiling on the walls of your coolant passages.  This means more liquid (and
less vapor) is in contact with the cooling passage walls, which means more
heat can be transferred away from the metal.

When I used it in my '83 CGT, I had just acquired the CGT and it tended to
run a little warmer than I thought it should.  So I flushed out the coolant
and ran the Special Blue Stuff required by Audi for my car's engine
(phosphate-free antifreeze, Autobahn brand, purchased from the recently
retired Linda @ Carlsen).  It ran hotter after the RLWW, a LOT hotter, and
it ran hotter the more cold air went over the radiator.  Weird.  At this
point I looked at exactly how the CGT's cooling system worked, and started
scratching my head.  

The Audi cooling system (at least on my I5 -- haven't traced down the V6 in
my wife's car) is backwards from all the other cars I've ever fiddled with
to any extent.  That is, on the Audi, hot water flows unimpeded from the
head into the top of the radiator at all times; the water is cooled, sinks
to the bottom of the radiator, and then gets drawn back in THROUGH THE
THERMOSTAT by the water pump.  (Other cars, if you haven't looked, have the
thermostat on the head, where it controls the flow of hot water out of the
engine.)  I'm not positive that this is why the RLWW failed to work for me,
but one plausible explanation could be that the RLWW provided enough extra
cooling in the radiator that the water on the entry of the thermostat was
cold enough that the thermostat stayed closed.  

So I drained the RLWW and went looking for other reasons the car might run
hot.  Turns out I had two hardware problems at the time: a non-operational
radiator fan switch and a leaky hose to the overrun tank.  By the time I
fixed those and refilled the CGT with water and whizzy blue coolant and no
RLWW, the cooling system ran flawlessly for about two years.  

Then I lost a heater hose (driving with the air on at 105 degrees ambient
temperature stuck in traffic a year ago next Friday) and overheated; I
replaced ALL the hoses after that, but the car still ran a little hot,
verging on a LOT hot at times.

Inspection of the system components turned up two pieces of collateral
damage from the overheat episode: first was the pressure cap.  Our own
sainted Phil Payne pointed out on the Q-list that pressure caps are
single-use items; if the car overheats and blows pressure, you need to
replace the cap.  I did; it was better but not right.  So I checked the
thermostat, and it was stuck partially shut.  I replaced the thermostat,
refilled the system with water and Blue Stuff, and the cooling system has
run perfectly ever since.

Morals of the story: 1 - RLWW doesn't fix hardware problems; if your system
has leaks, inoperative switches, stuck thermostats or blown pressure caps,
RLWW will not magically make it right.  2 - there are some distinctive
features of the Audi cooling system which make generalization from other
cars questionable, so if you think you're not getting all the cooling you
should, look for dodgy components first.  

The conclusion I came to is that RLWW *may* make a properly running Audi
cooling system run cooler, but once I got my Audi cooling system running
properly, I  didn't need the RLWW for my application.  However, I don't run
these Audis on the track; if I were consistently seeing 5000 RPM plus and
hard throttle usage (as I do in the Alfas), I might look into RLWW again.
But in either case, I'd check the rest of the system first.


--Scott Fisher
  Tualatin, Oregon

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