Why Is Milk White?: & 200 Other Curious Chemistry Questions (2013)
3. Household Chemistry
Why do you need antifreeze in your car?
If you live in a place where the temperature never drops below freezing, you don’t need antifreeze. But, as mentioned in the last answer, the antifreeze ethylene glycol also raises the boiling point of water, so you might still want to add it to your radiator water so the car doesn’t boil over as easily as it would with water or a combination of alcohol and water.
Commercial antifreeze also contains rust inhibitors—silicates, phosphates, and borates—to make the engine last longer. These control corrosion by keeping the liquid slightly alkaline. A green or red dye is also added so you can tell antifreeze from other liquids that might leak under your car. Orange-dyed antifreeze has rust inhibitors made from organic acids, which last longer.
Another antifreeze ingredient is diethylene glycol, although usually it is found in much smaller amounts and sometimes only because it is an unwanted byproduct of ethylene glycol production.