Why Coolant Additives
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by Steve Jack
Okay...here's my speeeeal on these and why I use them. I think you will change your mind about some of
these after doing some simple research. I used to be a little skeptical about some of this. However,
after doing much research in the cooling and coolant areas my mind was changed a couple of years ago.
Now I am NOT saying that this stuff is going to make an appreciable difference on your temperature
gauge per se and the benifits of these products are hard to put a yardstick to since we don't directly
see the evidence. But, a chemist from Prestone taught me most of this and how these additives work.
I am a believer now. Your decision is yours!
Actually even tho these products are marketed toward problematic areas in general, the additives are
in fact worth using under normal circumstances too... AND most of the newer coolants are employing much
the same additives I might say, according to Prestone engineers. Both EG and PG coolants have some
sort of surfactant additive added and in most cases are the identical chemical concoction found in
these additives! So they see the worth too and obviously antifreeze 10 years ago was pretty mundane
compared to today's complicated products. So, these additives have played an improvement role,
especially with advent of aluminum parts etal and smaller radiators.
Also, take into account that many of US are not running the "perfect mix" of 50/50 mix per se,
something that the coolant industry designs its products for specifically, therefore the surfactants
and additives that is in the original product is diluted to an extent depending on mixture, so a
surfactant/additive is quite appropriate in any in most cases and even with a 50/50 mix as well I
would argue.
My research shows that these products provide excellent protection from cavitation erosion in the
water pump and cylinder head. Localized boiling in the cylinder head forms vapor bubbles which collapse
when they come in contact with cooler liquids. This collapse creates tremendous shock waves which
removes the inhibitor film from the aluminum surface and can cause catastrophic erosion of the
aluminum if the inhibitor does not reform the film quickly. Another problem created by cavitation
erosion is the deposition of the removed aluminum as a salt with poor heat transfer properties in the
lower temperature radiator tubes. These products prevents this corrosion through effective film
formation and smaller vapor bubble formation, which has a less violent collapse. Foam control is
equally important since entrained air will cause cavitation erosion due to the collapse of foam
bubbles. These products provide excellent control of foam with water alone and glycol solutions due
to their "surfactant actions".
Now understanding the chemistry and its worth, I run these for several reasons really. First,
surfactants help alot with getting air out of the system completely. Second, I run high flowing pumps
in all my engines with "overdrive" technology. This means at 6500rpms indicated on the Camaros tach,
means the water pump is turning at a whopping 7600+rpms and keep in mind it's a high flow pump! I do
not want to induce cavitation and air in places I do not want it, therefore the "surfactant action" of
the additives will help alleviate this air problem. I have seen this with my own two eyes in test
tanks. The secondary feature of inhanced heat transfer does not help me per se, because I am like you
guys (Ed and Deuce) and design systems that are adequate, but if I ever lose pressure or coolant the
edge might get me to a safe haven just in case. Third, there are corrosion inhibitors abound in these
additives and with less than a 50/50 mix, with all the aluminum parts that my cars engines have (water
pumps, heads,
intakes, radiators) this is further insurance against electrolysis and corrosion by keeping the coolant
at the correct PH levels.
The benefits of WaterWetter or Purple Ice are:
Also, some cooling systems are on the ragged edge regardless of design due to footprint design or area
limitations etc. I get over 100 emails a month on either cooling or electrical issues from various
articles. I cannot tell you how many times some rodder has stuck a beheamoth 502/502 in a 67 NOVA and
can't get it to cool in Texas. He may have the largest/most efficient radiator he can get in there too.
His sytem is usually on the edge of cooling. By adding a high flow pump, a higher CFM fan and some
water wetter he has made a huge difference in heat transfer and is happy as a lark. The additive
helps build a cushion due to its ability to move heat faster.
So, you can do what you want, but in my experience and after learning all it's attributes, it's a no
brainer and cheap too. I hope I can change some of those "rodding" minds.
That's my story and I'm stick'in to it ;)
Acidity and alkalinity is measured on a "pH" scale, where 7 is neutral, lower numbers represent
increasing acidity and higher numbers increasing alkalinity (pH is chemist talk for the concentration
of hydrogen ions in solution). Pure water is neutral with a pH of 7. Battery acid reads 2 or 3 on the
pH scale, while baking soda might rate a 10 or 11.
Whether the coolant is acidic or alkaline makes a big difference. As long as it remains alkaline,
corrosion is inhibited. But if it goes acidic, corrosion starts to eat away at the interior of the
system. The corrosion-inhibiting additives in antifreeze are put there to keep the solution on the
high side of the pH scale. The alkalinity of a typical antifreeze/water mixture will vary depending
on the additives used and ratio of ingredients, but is usually somewhere between 8 and 11. The average
for most antifreezes is around 10.5, but when diluted 50/50 with water and added to the cooling system
the pH drops to the 8.5 to 9 range. Higher is not necessarily better, though, because some of the new
long-life coolants have a pH of only 8.3. Staying power is what counts.
This point speaks to my diatribe above about corrosion inhibitors.....To ensure that the coolant
remains alkaline for a reasonable length of time, there must be enough corrosion inhibitor to
neutralize the acids formed from glycol degradation that occur over time. This neutralizing capability
is called "reserve alkalinity," and it varies depending on the type and quantity of additives used in
a particular brand of antifreeze.
Heat, dissolved oxygen, minerals in the water and corrosion inhibitor reactions at the metal surface
gradually "use up" the corrosion inhibitors; once depleted, the coolant becomes acidic and corrosion
accelerates. The trick to preventing internal corrosion, therefore, is to change the coolant before all
the reserve alkalinity has been used up.
Test strips are commonly available from your favorite parts store. Just do it to protect your aluminum
parts. Steve Jack
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