Antifreeze choice

[Duke W.]

If your want to sort out what is probably your confusion on all the current antifreeze choices, download, print, read, and save the following pdfs.

The knowledge here should allow you to make a proper choice for just about any modern or vintage car.

Traditional "green" antifreeze is being phased out by most manufacturers, and though it provides good corrosion protection, it also clogs up radiator and heater tubes in the long run, which is why NO OEM uses it anymore.

If you don't come to the conclusion that Zerex G-05 (or an equivalent blend if you can find one - I'm not pushing specific brands - just providing information on brands that are widely available and provide information on what their product is) is the best choice for a vintage Corvette or most other vintage cars that were originally equipped with "green", read the material again. The second link is a download available on the Valvoline web site and they also have detailed spec. sheets on all their antifreeze products.

Note that Zerex G-05 meets GM specifications 1825M and 1899M. This is clear on both the spec. sheet and product label. These are the pre-Dexcool specifications in effect prior to GM's switch to Dexcool ten years ago. This HOAT blend will provide equal or superior corrosion protection to "green" without clogging up the tubes.

Several have asked me about current Prestone products, but I have not been able to sort them out with either the label or website information, and if I don't what an antifreeze product is, I don't buy it.

The various antifreeze "technlologies" referred to in these articles are the type of corrosion inhibitor package. ALL are ethylene glycol based. NO OEM that I am aware of recommends a propylene glycol base product, such as Sierra brand or Evans NPG, and I do not recommend them, either.

http://www.motor.com/magazine/pdf/082004_04.pdf

http://www.valvoline.com/downloads/DTurcotte_Mag_53_g.pdf

Duke

[Donald B.]

Re: Antifreeze choice

Your research was good enough for me. It is G-05 for me. Don't want anything freezing up here in frigid So. Cal. !

Thanks for all the research !

[Kent K.]

Re: Antifreeze choice

Duke --- I have one simple question. If there is a small amount of the previous antifreeze remaining (Prestone as I recall) in the coolant system when one changes to Zerex G-05, will there be an adverse reaction of the mixture?
Thanks, Kent #6201

[Duke W.]

Re: Antifreeze choice

It is best to do a thorough system flush to remove as much of the old green as possible. This is best accomplished by removing the heater inlet hose at the inlet manifold and flushing both the engine via the manifold nipple and the heater core circuit.

Duke

[Howell Jaynes]

Re: Antifreeze choice

Maybe I don't quite understand the "green" stuff. The long time standard for "anti-freeze" is ethylene glycol. World War fighter aircraft used 100% ethylene glycol coolants. They did not use any water. An acquaintance of mine was a Army reserve tank mechanic and he said that the Army tanks all used 100% ethylene glycol. I've used 100% ethylene glycol in my 1968 Corvette since about 1974. There is absolutely no rust in the engine block and I still have the NOS aluminum radiator that I installed in 1974.

I think ethylene glycol is the green stuff. It is extremely benign. It's heat transfer capability is a little less than water. If you have a copper radiator Corvette with Air Conditioning, pure ethylene glycol may not work for you. One advantage is that it boils at 265 degrees F. With pure ethylene, you cooling system will not pressurize so you have less problem with a hose bursting, etc.

I understand the really "hot" setup is to go with propylene glycol. This stuff boils at about 350 degrees (??) and this is used in racing engines to avoid hot spots in the heads. Also, in Switzerland, ethylene glycol has been banned since it's toxic (to animals and small children since it has a very sweet taste). Propylene is not toxic. Actually it's commonly used as a food additive. Propylene is not cheap. It's about $10 a quart.

Anyhow, if the "green stuff" is really ethylene glycol, it is very harmless for your engine and I suggest using it 100%. ( Unless perhaps you have a copper radiator C2, C3 BB with air conditioning.)

[Duke W.]

Re: Antifreeze choice

I suggest you reread my initial post and download and read the referenced pdfs. You have a lot of misconceptions.

"Green" antifreeze is ethylene glycol based and has an IAT inhibitor package, which is considered obsolete and is no longer used by any OEM.

The new OAT and HOAT antifreezes are also ethylene glycol based and provide better protection and longer life without clogging the system up with precipitates.

But didn't I already say the above in my initial post?

Liquid cooled WW II aircraft engines did use straight ethylene glycol, but modern automotive cooling systems are designed for the heat capacity of a 50 to 70 blend of ethylene glycol and water, and the corrosion inhibitor packages are optimized for dilution with water in the above ratio range.

Corrosion inhibitor technology, if it even existed in the 1940s, was in its infancy.

I am not aware of any OEMs that use or recommend propylene glycol (but I already said that) and GM specifically recommends that it NOT be used.

If you want to use antifreeze concentrations outside the 50-70 percent GM recommended range or believe aftermarket vendor advertising hype about non-traditional coolants, that's your choice.

Duke

[Howell Jaynes]

Re: Antifreeze choice

When I removed the water pump off of my 1968 Corvette SB with an aluminum radiator a few months ago, I can look in the engine and see only a white appearance to the internal water passages of the block. There is no rust or slime. All I see is a white colored film. I still have the original copper heater core in my 1968. I have used pure ethylene glycol in my 1968 since about 1973. Actually I don't care about anti-corrosion additives to my ethylene since with pure ethylene, I dont need anti-corrosion additives. The ethylene gylcol is a dielectric and doesn't conduct corroding currents from dissamblar metals.

In 1973, my original aluminum radiator started leaking. An acquaintance of mine also worked as a tank mechanic in the Army Reserves. He said the tanks all used pure ethylene. He advised me to replace my radiator and then use pure ethylene. I did with a NOS radiator, and have never had any problems since. I understand that some of the NASCAR engines now are running pure proplyene glycol. Proplyene has a much higher boiling point and this is considered an advantage for avoiding cylinder head hot spots.

But anyhow... for NCRS people. If you want to really protect your cooling systems, pure ethylene glycol will absolutely protect your radiators and radiator cores. I've worked as an Aerospace engineer for 43 years and I would like to say that water in hydraulic, pneumatic, cooling lines is lethal. In government systems I've worked with, water is NOT TOLERATED. (The only caveat, is that some of the C2's and C3's, especially BB's with AC, had marginal cooling systems and the loss of efficiency of not using water can cause heating problems.) This is my experience. I'm just relating it. If you don't want to believe or agree, that's OK with me.

And if you just really have to use water, make sure it's de-ionized water. Pure distilled water will work.

[Bill Richards]

Re: Antifreeze choice

Howell, I agree with you. I researched this topic in 1970 for my 66 roadster and came up with the same info. as you are posting now. 100% ethylene glycol was bullet proof in corvetts back then. There may be better antifreezes out there now, however I think the 100% rule should still apply..... Bill

[Duke W.]

Re: Antifreeze choice

All commercial antifreezes have about 10 percent water. It's a byproduct of the manufacturing process, so commercial "pure" ethylene glycol is an electrolyte.

The ABSOLUTE WORST thing you can put in your cooling system is straight deionized or distilled water.

The white deposits you see in you cooling passages are the silicates and phosphates that are precipitating out of the antifreeze. They act as an insulator, especially in the radiator tubes.

Most alumninum radiators fail due to "arterial schlerosis" - deposit buildup in the tubes from the inorganic salts that were used in green antifreeze to prevent corrosion. These salts prevented corrosion, but clog and "insulate" the tubes, so eventually the radiator's heat transfer capacity is degraded to the point where the engine runs hot or overheats. Modern OAT and HOAT antifreezes provide excellent corrosion protection without clogging up the tubes.

I've got nearly 40 years in auto and aerospace engineering, and I've studied a lot of corrosion control issues with emphasis on automotive engine cooling and corrosion control. It helps with lowering maintenance and repair costs when you have a stable of cars - all bought new - that are 15 to 43 years old.

My information comes from published technical papers and articles in industry trade magazines, not anecdotes from mechanics and internet chat rooms.

Duke

[Rick S.]

Re: Antifreeze choice

Duke,
What water do you recommend to use with the Zerex G-05 to obtain the 50-50 ratio?

[Howell Jaynes]

Re: Antifreeze choice

I really disagree with about everything you wrote, expecilly the de-ionized water. However, I really have no desire to continue the conversation. I'm really quite happy using pure ethylene glycol, as I have for the last 30+ years. Actually, when I get my rebuilt 68 engine running, I plan on using 100% propylene glycol. (It's not toxic). The boiling points of ethylene and proplyene is much higher than water.

I assume that I will, as I have for the last 30+ years, continue to read about people's problems replacing radiators, heater cores, etc because they prefer to use water in their engine cooling systems.

[Duke W.]

Distilled water *NM*

[Duke W.]

Re: Antifreeze choice

You might want to update your 36 year old information.

Duke