The Importance of Coolant

Whether you call it engine coolant or antifreeze, the fluid in your radiator multi-tasks, circulating throughout your engine block and keeping the works purring like a kitten.

What is Coolant?
Generally, coolant is a half-and-half mixture of a form of glycol and water. The glycol represents the antifreeze element of the mix, guaranteeing that the fluid doesn't turn into ice under harsh winter conditions. On the other hand, glycol also prevents the coolant from reaching the boiling point in Death Valley heat; it keeps engine temperatures stable under all climate extremes and driving conditions.


Interestingly, pure water actually transfers heat better than coolant (that's why you see straight water used in the radiators of some types of racecars). However, coolant/antifreeze includes additional additives that prevent rust and corrosion in the radiator, engine and the vehicle's heater.


Until recently, the most common glycol in antifreeze was ethylene glycol, a toxic material that can cause birth defects, reproductive damage or even death if ingested, and requires very specific handling. Ethylene glycol has a sweet odor and flavor, which makes it dangerously appealing to animals and/or small children.


An alternative antifreeze base is propylene glycol. There is very little difference in the performance of either substance; the advantage is the toxicity level. Propylene glycol is significantly less toxic than ethylene glycol. This doesn't mean children or pets can ingest it without harm, but, like alcohol, propylene glycol is not toxic at low levels.