Anyone have experience with the extended life Prestone Antifreeze/Coolant promoted as mix with any color antifreeze, new formula, all makes, all models? Is it the same as Dex-Cool, better, worse or stick with the green stuff? TIA
Interesting...Will have to research this one...
I have read in several places that it is essentially Dex-Cool dyed yellow and without GM licensing. I am not sure if that is true or not.
John
Interesting. I dont know whether GM owns any patents in this area, but can check it. GM would almost certainly own the rights to the Dex-Cool name. The first patents I read in this general area of chemistry were by Japanese researchers.
As I have mentioned before, the company I worked for used this technology but bought the additive package from the patent holder, and was therefore free to use it in glycol formulations.
I took a quick look, and it would appear that Texaco supplies the inhibitor package to GM. This organic acid technology (OAT) was supposed to be great stuff and free of silicate. HOAT was then formulated to offset some of the OAT problems, and silicates were added again, but at lower levels.
BASF apparently also supplies some materials.
Again, I dont believe GM has a licensing position, but am no lawyer.
I tried to read the page but it is too deep for me. However, the following caught my eye, does this apply to DEX-COOL?
Alkylene glycol/water mixtures are very corrosive at the operating temperatures of internal-combustion engines. For this reason, the various metals, such as steel, cast iron, copper, brass, aluminum, magnesium and alloys thereof, as well as solder metals, for example solder tin, which are used in the cooling system have to be adequately protected against a very wide variety of types of corrosion, for example pitting corrosion, crevice corrosion, erosion or cavitation, through the use of corrosion inhibitors.
New formula Prestone contains ethylene glycol, diethylene glycol, sodium 2-ethyl hexanoate and sodium neodecanoate. Isn't ethylene glycol the basic ingredient in green stuff?
Ethylene glycol is the basis for both the old green stuff and most of the new formulas too. Some are using propylene glycol since it is less toxic to animals, but it is also less effective and more expensive.
That patent that I posted is very similar to the Dex-Cool formulation. BASF owns that patent, I believe, but other similar ones are owned by other companies or individuals. I believe the corrosion inhibitor package for Dex-Cool comes from Texaco. We could search Texaco patents and pin it down further.
There is a lot of chemistry tapdancing that goes on in patent work.. people patent around other patents by changing a little here and a little there. Simply having a patent doesnt mean that the product or process has been tested, that it ever existed except in somebody's mind, or that it is effective.
I visited the
EXTENDED LIFE Antifreeze/Coolant New Prestone® Extended Life Antifreeze/Coolant is compatible with ANY antifreeze/ coolant - regardless of color - for use in ALL makes and models of cars and light duty trucks. This patented formula provides a high degree of performance durability and carefully balanced protection against temperature extremes and rust corrosion of all cooling system metals, including aluminum.
EXTENDED LIFE 5/150 Antifreeze/Coolant Prestone® Extended Life 5/150 Antifreeze/ Coolant is recommended and formulated for use in all vehicles that require DEX-COOL® coolant, as well as all other cars and light duty trucks with aluminum radiators using extended life coolant. This patented formula has a concentrated blend of premium long-lasting inhibitors for extended performance, protecting against temperature extremes and the ravages of rust and corrosion for 5 years or 150,000 miles. DEX-COOL and GM are registered trademarks of General Motors Corporation.
Wasn't silicate the problem ingredient in DEX-COOL?
I believe that Dex-Cool was silicate free - the so-called OAT (Organic Acid Technology). Maybe that is why it fell a bit short of the mark.
HOAT is Hybrid OAT, and some of the silicate has been added again, although not as much as previously.
There is considerable leeway as to which organic acids can be used in these blends.
One of the old technology packages had 0.2% sodium metasilicate as the inhibitor. Now, only a very small amount of that package was blended into ethyleneglycol to make the market ready antifreeze, so you would have had only parts per million of silicate there. Even so, occasionally you would see problems with it.
I found a series of patents, including one which I believe Prestone is currently using.
All that I can say is that short term corrosion testing often makes chemicals look better than they turn out to be during long term application. For example, anybody's fresh ¨ antifreeze with the corrosion inhibitor package installed in a clean engine with good water may give good results.
As that system heats, cools, sucks air in, gets a little rust or pitting, etc, the nature of the corrosion reaction changes. The inhibitors may no longer function as well as they did in the clean engine. Before you know it, you have a problem.
Another example which may be interesting to you...in oil well acidizing, hydrochloric acid is used to improve flowability of oil zones, to clean everything up. But, hydrochloric acid is very corrosive, especially when it is very hot downhole. I remember some tests ¨ where companies had developed special corrosion inhibitors which would allow hydrochloric acid to be used at high temperatures, and it would hardly attack the bare steel pipe at all...in the lab. It was later shown that as soon as the hydrochloric acid dissolved a little rust, the inhibitor performance fell off badly.. It essentially stopped working because it had been 'poisoned' by a little contamination.
The rush to patent, and the rush to market, sometimes does more harm than good.
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