One of the most effective coolants for water-cooled engines is, you guessed it, water. Water is a good heat conductor and has a high heat capacity, meaning it can absorb a lot of heat. However, as we all know, it freezes solid at low temperatures, becomes ineffective as a coolant and downright destructive as it expands, thus the need for some replacement liquid or additive to achieve a greatly lower freezing point. Behold, antifreeze.
The antifreeze I recall first knowing of was called temporary antifreeze. That was back in the ‘40s. Our family was fortunate enough to own a 1940 Chevy. As automobile production plants were converted to WWII military equipment, new car production for civilian use ceased in 1941. I recall the glass jugs my dad stored down in the cellar containing a red liquid that looked like wine, perhaps a pinot noir. That was temporary antifreeze. In the fall, Dad would drain the radiator and refill it with this red liquid, which I think was probably ethyl alcohol. In the spring, he reversed the procedure. This temporary antifreeze wasn’t as good a coolant as water for summer use but it did the job in winter.
Antifreeze/coolants on the market today are year-round, permanent coolants. You can be excused for being confused by the vast number of different types on the shelf. They are of different colors and designated for American, European, and Asian car makes. Of the Zerex line, I counted four different types for American cars, three for Asian, and five for European.
They are all composed of ethylene glycol with different additives to provide resistance to corrosion. It’s these additives that distinguish one type from another.
Ethylene glycol is technically an alcohol. It’s slightly denser than water, has a significantly higher boiling point (387 ⁰ F) and freezes at 8.8 ⁰ F. That freezing point number wouldn’t be too impressive but for an important scientific consideration. A mixture of two liquids can have a freezing point lower than either of the compo-nents. The concentration at which the freezing point is lowest is the eutectic point. For ethylene glycol and water, this point is at 55% ethylene glycol with a freezing temperature of -61.6 ⁰ F. Most often these anti-freezes are sold as a 50% concentration. The squeeze bulb gadget you can buy to test the freezing point is simply testing the density, which the scale correlates with freezing temperature.
When faced with the need to top off your coolant reservoir, you’re bound to wonder which type of antifreeze to choose and if anything awful will happen if you pick the wrong one. The conventional wisdom is that mixing different types can be bad because the additives can react with one another to form some gelatinous goo that will plug things up and reduce circulation.
You’ve also got to wonder why it matters what continent your car is manufactured on. It really doesn’t. All modern cars have engines made with cast iron and aluminum parts bolted together and have the same corrosion susceptibilities due to electrolytic cell reactions that wouldn’t occur in our old vintage engines with all cast iron engines. What’s good for one modern engine is good for the others. What matters is what kind of antifreeze/coolant they put in at the factory. When in doubt, check the owner’s manual.
I’m not much of an exemplar of obsessive antifreeze correctness. Back in the ‘70s I used to buy used antifreeze from the local junkyard to use in my tractors. I think much of it is still in there and it’s doing its job just fine with no ill effects yet, and it’s been over forty years.
Leave a Reply