Identifying types of antifreeze

[Dave Henderson]

"IAT", Inorganic Additive Technology type is recommended for old cars and "OAT", Organic Acid Technology is said to be harmful.   However, the jugs that I observed don't say what type the contents are.  I'll pass along what I found out for Prestone and CarQuest (Advance Auto) brands, which took some doing to dig out.  The only IAT type that Prestone offers is their "Prime" with a GREEN cap.  (caps come in several colors)  CarQuest's, according to the AA store also has a green cap.  So it's easy, but too bad they don't just say what type it is on the jug....  Hope this saves someone some trouble. 

[JACK M]

Most claim to be all compatible.

[Spinneyhill]

Who says OAT is harmful in old engines and why? Remember that modern engines are much harder to protect from corrosion because they contain metals right at the top of the galvanic series: Al, Mg for example. We might have Al and perhaps Zn in the cooling system. My understanding is we don't NEED the extra strength of OAT and it won't do any harm. All the bottles I read in the shop say compatible with all metals.

 

Search these fora. There are very many topics on antifreeze.

Edited November 26, 2019 by Spinneyhill (see edit history)

[Grimy]

Don't have time to look for it now, but a Rolls-Royce Owners' Club article of several years ago reportedly claimed that OAT is incompatible with certain types of SOLDER used in pre-war radiators.  I certainly welcome any definitive answer.

[Joe in Canada]

6 hours ago, Spinneyhill said:

Who says OAT is harmful in old engines and why? Remember that modern engines are much harder to protect from corrosion because they contain metals right at the top of the galvanic series: Al, Mg for example. We might have Al and perhaps Zn in the cooling system. My understanding is we don't NEED the extra strength of OAT and it won't do any harm. All the bottles I read in the shop say compatible with all metals.

 

Search these fora. There are very many topics on antifreeze.

It does not damage the engine but it does damage the copper rad. The new stuff eats the solder joints and I have seen samples of what it does. The new improved formula saying it is compatible with older cars they are referring to cars 10 years old. I do have the article somewhere on my computer from RR and will repost it again when I come across it

[Bloo]

Don't let any of my radiators hear you say that!. I have been using those newfangled formulas in practically everything since about 1986 when a salesman talked me into trying it. I sure don't have much radiator trouble, but I'm still waiting.....

 

One of those cars is a 1991 Geo Metro with over 200k on the clock. Dex-Cool since 1996. The radiator is a copper core with plastic tanks. The heater core is conventional brass/copper. The radiator is beat to hell from rocks on the lower half, but it doesn't leak. I had the dash and heater out of it in 2012 when repairing some very old body damage. I had the heater core out and in my hand. It still looked brand new. I put it back in.

 

Another car I owned went well over 100k after being switched to modern coolant. I don't have the car anymore, but I still have the radiator.

 

GM did have a bunch of trouble in the 90s. Those cars had aluminum radiators, not copper. They told people they could leave the coolant in for 5 years. The coolant became acidic and ate the aluminum heads. I can't help but wonder if that 5 year thing had something to do with US emission warranty law. Coolant eating aluminum heads, copper radiators, and other parts is nothing new. All that happened with the old-style coolant too, when people did not change their coolant for years.

 

I remember Alfa Romeos having the aluminum heads eat through to the combustion chamber when people did not change their coolant. It became fashionable to stick a sacrificial anode made of magnesium in the head to prevent corrosion. My 1975 Alfa still has it's original head and it's original copper/brass radiator and original copper/brass heater core. No sacrificial anode. Dex-Cool since the summer of 1995. No trouble with any of it so far.

 

Change your coolant every year or two. Use only distilled water. 5 years is too long no matter what the bottle says. If you do that you are gonna have a bad time.

 

I keep hearing the sky is falling. I keep looking up. I'll let you guys know if I see anything.

 

 

 

Edited November 27, 2019 by Bloo (see edit history)

[Spinneyhill]

3 hours ago, Joe in Canada said:

it does damage the copper rad. The new stuff eats the solder joints and I have seen samples of what it does.

Sounds to me like they left it in too long and the anti-corrosion additives were worn out. Frankly, I don't believe it. That is why it was developed: copper against metals like solder contains! And they tested the coolant after discovering the damage? The bottle says ALL metals, not older cars.

[Joe in Canada]

What new cars have a copper rad today?

[trini]

It is time the different car clubs get together and lobby  the Consumer Department to force the coolant manufacturers to divulge the chemical make up of their product.

[R Walling]

 All the new class 7-8 heavy trucks demand that you use a special coolant that is designed specifically for their engine.

Edited November 27, 2019 by Roger Walling (see edit history)