Coolant/Antifreeze options

Dr.Jeff

True Classic
I really hesitate to even bring this up because I'm sure it will turn into another "what's the best oil" debate. :rolleyes: So please note I am NOT referring to any brands, colors, or other choices. This is solely about the "types" or chemical properties of coolants. ;)

Unfortunately there isn't a uniform classification system to describe the different types (formulas) of coolants available. But there are a couple of commonly used ones (at least for import vehicles); the "BASF" system and the "VAG" system. Even better, there are basic chemical composition formulas that classify them. Start by reading this article that offers a simple explanation of each:

Older Euro cars would typically be the "IAT" (e.g. G11) type. However that is becoming a little more difficult to find and therefore more expensive. In most cases you may need to order it online with the associated "hazardous materials" shipping expense (usually more than twice the cost of the product itself). It has the least cooling properties of all types, which doesn't help the X's marginal cooling system design (not open for debate in this discussion :D). And it has potential issues with corrosion in vehicles with a cooling system using mixed metals (cast iron, aluminum, brass, copper). Furthermore this type has the shortest service life - usually 2 years. Some of my hobby cars will sit that long without any use. :( Basically it is the oldest technology of all the types out there.

Many of the newer "OAT" and "HOAT" types (e.g. G12, G12+, G05, G30, G48) have a longer service life - 3-4 years. But they are not a great choice for other reasons (see related articles for details). Especially if you still have the factory brass radiator. And it is not compatible with the earlier type (G11) so the entire cooling system will need to be thoroughly cleaned prior their use. However they are more readily available at most local parts stores and therefore more affordable.

The latest category of coolant ("Si-OAT") (e.g. G13, G40) is supposedly compatible with pretty much all cooling systems and with all other types of coolant. Regardless what radiator you have - stock factory or upgraded aluminum - then there's no issues like some of the others have. It offers the highest cooling properties, the longest service life (5+ years, which is really nice for hobby cars that tend to sit for long periods), is readily available, and is also much better for the environment if you are into that. The possible drawback is it is more expensive than the intermediate ones. I'm wondering if this may be the better choice for vintage cars like our X's?

As one might expect there's a lot of garbage on the internet about coolants, just like with oils, spark plugs, filters, etc. And with that comes mixed information about each of these coolant types. So it's difficult to know exactly what to believe. Not to mention my chemistry days were a long time ago. Hopefully we have some chemical engineers here that can shed more light on this?

Finally, please do not refer to any of the coolants by their color. Unfortunately various manufacturers utilize all sorts of colors for any/all of the types. So the color is definitely NOT a reliable means of identifying them. If possible please refer to the general chemistry type (IAT, OAT, HOAT, Si-OAT, etc) or by one of the two more common classification designations (BASF or VAG) to help avoid confusion. :)
 
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I'll try to compile a folder of them later, but Glysantin (referenced in the article) has tons of data sheets regarding each coolant, and how they interact with metals (copper, solder, iron,) and so on over a given period of time- it may be something worth using as a source of scientific data, preventing the discussion from going how "the best oil" discussions tend to.

Quite easy to find on Google, with searches like "Glysantin Gxx" data

I'm definitely very interested to see what proves to be most ideal, as I intend to change away from G48 once the system is put back together (due to its sub par performance with Solder), and it's been hard to find solid data on what works well on this platform (mainly, which metals the system contains being the biggest factor)...by the sounds of it we have the whole periodic table present and accounted for in our systems.
 
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Here's the section of the data sheets showing metals compatibility for g05,G40,g48 and g65. I'm still missing g30 as it won't download for whatever reason. The test results there shouldn't be taken as gospel because the majority of them (it states) are done in a lab environment that doesn't stimulate everything that may have an impact in a real world scenario.
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This is solely about the "types" or chemical properties of coolants.

Great point - I'm going to drain and refill my system again. I did it last in 2015. I used Prestone OAT coolant as I didn't really consider that it wouldn't be compatible. Previously the coolant had not been changed for a very long time!

I was going to use Prestone OAT again. I don't know if that's good or bad. I used it in my other classic and so far it's been OK. I like that it is now a 10 year coolant as I don't feel like doing it every two years (as you would with IAT).

I don't have an aluminum radiator.

Hmm...
 
Great point - I'm going to drain and refill my system again. I did it last in 2015. I used Prestone OAT coolant as I didn't really consider that it wouldn't be compatible. Previously the coolant had not been changed for a very long time!

I was going to use Prestone OAT again. I don't know if that's good or bad. I used it in my other classic and so far it's been OK. I like that it is now a 10 year coolant as I don't feel like doing it every two years (as you would with IAT).

I don't have an aluminum radiator.

Hmm...
I am curious about the Platinum coolant:
15 years which truth be told some of my cars have been carrying around the same fluid for longer than that (With no ill effects so far but…)

Last summer I took apart my gold X’s coolant system and cleaned out the radiator and heater core with several fillings of vinegar, removed the lower access port on the hot, high intake side of the radiator which allowed me to clean out a small pile of guck at the bottom, flushed the pipes, head and cleaned the castings for the thermostat. By and large everything was clean and non corroded (thankfully), I was honestly surprised because I had been quite remiss for many years on this car. (Hanging my head in shame)

Anyway curious about a long life product just because…
 
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