What are suitable coolants for aluminum engine + brass+soldered radiator?

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I'm no expert on this. Here is an old 2004 article by a knowledgeable man that recommends conventional IAT coolant: https://www.motor.com/magazine-summ...easy-being-green-or-yellow-or-orange-or/

"Original equipment coolants are validated for factory replacement parts. One of the issues that may arise is the use of an aftermarket replacement radiator or heater core made of copper-brass with lead solder. We have in previous articles pointed out that today's coolant inhibitor packages contain a small amount of copper-brass protection, but may provide little protection if a radiator is made with high-lead solder. Results of industry standard tests of the new Toyota extended-life coolant now show a substantial weight loss (corrosion), both in a 50-50 mix and in a 33% coolant mixture (solder corrosion is much greater in this more diluted solution).

If you have to change a radiator or heater core, use aluminum. Or, if it's an older car and the owner wants the lowest-cost radiator, you might procure a soldered-together copper-brass unit. Conventional American coolant should provide better protection against solder corrosion, which can result in radiator tube restrictions and leaks. But no coolant provides perfect protection."


Much has changed since 2004 and I don't know how these new long life coolants do with copper/brass/solder.
 
Good old green, NOT an AMAM/Dex-Clone. My pick would be the Zerex formulation, with low silicates and longer life. G-05 can also work and it's a non 2-EHA formulation also with borate and long-life protection. You need nitrate to protect solder, I think.
 
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Originally Posted by nthach
Good old green, NOT an AMAM/Dex-Clone. My pick would be the Zerex formulation, with low silicates and longer life. G-05 can also work and it's a non 2-EHA formulation also with borate and long-life protection. You need nitrate to protect solder, I think.

You don't need nitrate to protect solder.
The best protectors of solder are Benzoate and Molybdate.
A Silicate - Benzoate - Azole combo also gives good solder protection results.
 
I'm running G40 in my two Fords, ( what VW call G12++ , although the current G13 has the same inhibitor formula ) the particular brand i am using does not have 2-Eha but some do.
Zerex G40 i believe does not have 2-Eha, it lasts 5 years and really does a good job of protecting all kinds of metals, inclusing Solder, Copper, Brass, even Magnesium, it gives outstanding results for Aluminium corrosion and very good Cast Iron protection aswell.
 
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Toyota Red will work. Not the Toyota pink or the Zerex pink. It was used for cars and trucks that had the old school radiators like my 92 Toyota pickup. It's available in concentrate, but it's not cheap.

Toyota Red does not have silicates, but it does have phosphates and moly that FordCapriDriver pointed out.

The Prestone Green in the chart below is the old school green coolant. That's not what Prestone is selling now on the shelves at local stores in my area. Peak still makes the old school green with low silicates. I buy the Rural King house brand Durex that's made by Peak, and it's $8.99 a gallon for concentrate.





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I've retrofitted G-05/Premium Gold into several vehicles, including the ‘93 6.2 diesel in my sig that has a cast iron engine, aluminum/plastic tank radiator, & soldered copper/brass original 26 year old heater core-zero issues.
 
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