Antifreeze and Engine Coolant Overview

Understanding cooling systems will help you to make correct and accurate service recommendations, resulting in happy customers and increased sales and profit.

Almost all antifreeze products are based on ethylene glycol, including Dex-Cool and G-05 used by Ford and Chrysler.

Water is the essential heat transfer fluid, but, by itself, can be very corrosive to the cooling system. There are 3 qualities of water, classified by their content of calcium & magnesium:

  • Purified water

  • Soft water

  • Hard water

The terminology used as we discuss coolant system is important. Let's define a few important term:


Antifreeze is 95% ethylene glycol (or propylene glycol) that contains an additive package engineered to operate well when mixed between 40 and 60 % with water, the most typical mixture being 50-50.
Antifreeze has to be mixed with water to make coolant before being used. Ethylene glycol is poisonous, and should be handled and stored properly.


Engine Coolant

Engine Coolant is the liquid in an engine that provides heat transfer, i.e. 50 % antifreeze and 50 % water.


Supplemental Coolant Additive

SCA is a chemical package that is added to engine coolant to enhance and extend the life of the coolant.
Coolant has several important functions in the vehicle. It:

  • Removes excess heat from the engine
  • Protects the engine components against corrosion
  • Protects the engine against freeze damage incold weather, and
  • Prevents we sleeve liner cavitation in diesel engines