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Antifreeze mix ratio
Posted 08 January 2004 - 08:56 AM
I realize everyone's busy schedule prevents them from reading much but here is an excerpt any vintage Suby owner should read.
copy pasted from
Why a rich mix gives less cooling:
First of all, in this article, we refer to the stuff you buy simply as “antifreeze.” It comes under many different trade names, and for
automotive applications, is usually ethylene glycol. We'll just call it “antifreeze.”
Now if you've ever poured the stuff into a radiator, you no doubt observed that it is much “syrup-i-er” than water. That is, it has a much
higher viscosity. This means that it will not flow as fast through the system as water, and the cooling effect will be less.
Further, the specific heat of antifreeze is less than that of water. This means that for a given temperature change, the antifreeze will carry
less heat each time it circulates from engine to radiator and back.
So, if the mix is too rich, the cooling efficiency will be reduced because (1) the flow rate is less, and (2) less heat is transferred per cycle
of the coolant.
also for your reading
I doubt very highly if you have read this far, but with the cooling issues so many of us have..........
long since forgotten as summer has been over for several months,
this could be something to remember come June.
For those that have followed along, I thank you for your attention and
Remember to use distilled H20.
Posted 08 January 2004 - 10:24 AM
Glycol has a Specific Heat Capacity of 2.6 Kilojoules per degree per kilogram
Water has a SHC of 4.2 KJ/C/Kg
Only certain ammonias have a higher SHC, but these are unsuited for cooling. Water is the winner!
Posted 08 January 2004 - 10:45 AM
We should add that water has excellent thermal transfer properties also
water = 0.60 Watt/m · °C
Glycol at 0.25 Watt/m.°C
But alas you are correct when you say
"The only trouble is convincing people of these facts."
More excellent reading at
Thanks again for your suuport.
Posted 08 January 2004 - 02:10 PM
'91 Loyale 4wd 5spd Wagon
Posted 08 January 2004 - 02:44 PM
Dogs especially, but cats also like the sweet taste and will lick it up off the ground, so *be sure* to wash any puddles away. It causes their kidneys to shut down and they die a long, painful death.
Posted 08 January 2004 - 03:07 PM
but i can say when i buy antifreeze for my cars, i always use the prestone 50/50 mix stuff.. its always served my purposes well.. and its cheaper and ya don't have to figure out the mix yourself..
Posted 08 January 2004 - 05:59 PM
Posted 08 January 2004 - 06:25 PM
Posted 08 January 2004 - 09:27 PM
Posted 08 January 2004 - 09:31 PM
Orange antifreeze is extended life coolant developed for GM, called DexCool. Green coolant is also "especially formulated for aluminum engines." I saw several GM trucks come into the shop I worked at with rust plugs at the filler neck because they didn't have quite enough DexCool put in at the factory and the upper radiators rusted badly. Don't pay extra for stuff you don't need!
Posted 08 January 2004 - 10:32 PM
either way it didn't cost me anymore. it was the same price as one of those or two premixed. plus it looks "high-tech". lol:D
Posted 09 January 2004 - 02:19 AM
This is like the oil discussion: The most important thing is that you replace it at the correct interval. This is personal from car to car, because use and mileage vary vastly.
I do one cold-start a day. The rest of the day, the car is never stationary long enough to cool back down, and this means less condensation problems, and longer oil life. The coolant is also less stressed, because it is not cycled from cold to hot all the time, but remains at a fairly constant temp.
Posted 09 January 2004 - 02:55 AM
WHOAH! WAIT! STOP!
Putting orange coolant in your subaru at this point is NOT a good idea. Unless the manufacturer specifies a certain coolant, just use the green stuff. And definitely don't switch from green to orange at this point unless you get absolutely all of the green stuff out first. ANY mixing is really bad.
Orange or red coolants are specially formulated for specific types of metals, or systems that use two dissimilar metals, or whatever. The best coolant for your subaru is green.
Posted 09 January 2004 - 05:40 AM
Here is what I have found in reference to the above statements
With DEX-COOL®, the maximum ratio of antifreeze to water is 60/40.
Although DEX-COOL® type antifreeze can be mixed with standard ethylene glycol antifreeze, DEX-COOL® loses its 5 yr./150,000 life.
As such, it?s best not to mix antifreeze types unless absolutely necessary.
All coolants must be diluted with water at the proper ratios and should not be used full-strength.
Full-strength antifreeze actually has a
lower freeze point than when mixed with water.
Generally, standard ethylene glycol type antifreeze should be changed every two years or 24,000 miles.
Acid neutralization capability is very important.
Coolant which has been left in a cooling system for several years has probably become acidic from the oxidation of the glycol to acids.
Also, keeping the glycol concentration in the cooling system below 50% will help stability.
Once again I thank you all for your comments.
Posted 09 January 2004 - 06:13 AM
Posted 09 January 2004 - 01:47 PM
Posted 09 January 2004 - 09:56 PM
Nice VOICE OF GOD post there, bro!
However, extended life antifreeze actually has a maximum recommended mix ratio of 70/30 (I'm looking at the back of a bottle of Zerex and a bottle of Prestone). At that ratio, you are protected down to -84 degrees and up to 276 degrees - from that ratio up, you go down in temperature as you stated. Incidentally, standard antifreeze has the exact same mix ratio and temperature maximum/minimums.
I pulled up MSDS's on antifreeze and cannot find any mention of zinc in antifreeze. They have some complex chemicals that do what you stated, but no zinc.
I think, over time, if you are only running 25% mix, you are going to corrode your radiator, water pump, and coolant passages. Maybe not too soon, but eventually.
Posted 09 January 2004 - 10:22 PM
NOTICE skip says always use distilled h20 thats because its got no minerals and chemicals like tap water. only minerals will hurt your cooling system, not water.
Posted 11 January 2004 - 10:35 PM
I had waaaaaaaaay too much "prestone".............It was probably 95/5 .
I went to Safeway and picked up some distilled water, opened the drain and let out some coolant, topped it up with distilled and ran the engine for a few minutes to circulate the coolant.
I had to do this twice before I got it down to 50/50 mix.............
Oh, the heater really cranks now..........
Posted 11 January 2004 - 10:37 PM
Posted 12 January 2004 - 01:33 AM
i was mistakenly running 100% anti-freeze for about a week. last time i take some parts guy's word.
oh yeah, i used regular, run of the mill tap water. i just don't want to bother with the price of water. i have a new radiator and i should have started on the right track, but my car is a beater and i don't like to go overboard. i'm kinda in the market for a new car. i have some bills that i should pay and don't really need a new car, but i really want another sube.
Posted 12 January 2004 - 03:01 AM
Originally posted by Skip
I have a nasty habit of reading a lot, ---
I think it is a very good habit. Just don't forget to share your findings with us general public!
By the way, one of the sites you posted has another very valuable fiture:
For quite a while I was wondering what the heck my parts car was -- one dealership told me one thing, another -- another thing, tax office the same as 1st dealer, so ... Now I have a definite answer. Suppose this link would be worth posting in a separate thread?..
Posted 12 January 2004 - 06:55 AM
That site has a wealth of info for us car nutz.
Did ya peek at the DIY tool section?
Nice list of emerg. eq. there.
That could be a thread on it's own.
Something like that was on the "Off Topic" board I believe.
Posted 12 January 2004 - 09:40 AM
Posted 12 January 2004 - 10:59 AM
and ya don't have to pay more for the plain prestone then buy water.. the 50/50 premix is cheaper than the straight stuff..
just my .02 not that its amounts to much...
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