Types Of Antifreeze Explained

There are three primary types of anti-freeze for your car's radiator cooling system:

Ethylene Glycol/Polyethylene Glycol. Usually green in color. Tried and true, this type of anti-freeze is still standard after almost 70 years. Modern ethylene glycol anti-freezes have several additives to protect, clean, and lubricate your cooling system.
Non-Toxic Radiator Coolant. This anti-freeze does not contain ethylene glycol or polyethylene glycol (both acutely toxic). These engine coolants are, however, still toxic but only in larger quantities and over longer periods.
Extended-Life Anti-Freeze. Some are red/orange and some are gold. In most cases, this is simply an ethylene glycol anti-freeze with one or more carboxylate additives to prevent corrosion of the cooling system. These engine coolants should make your car radiator and cooling system last longer.

A word of caution about mixing antifreeze. While not inherently dangerous it is a good practice to not mix different types of engine coolant in the same system. You could damage or further reduce your car radiator's efficiency by mixing the different types. Before you change types, make sure to thoroughly drain and flush your cooling system.