Antifreeze Types / Definitions

May 16th 2020

Antifreeze / Coolant Description:

Antifreeze/coolant serves four purposes in a vehicle cooling system.

1. To lower the freezing point below 32º F / 0º C. (To help prevent freeze up)
2. To raise the boiling point above 212º F / 100º C. (To help prevent boil over)
3. To protect the cooling system against corrosion.
4. To lubricate water pump seals.

Types of Coolant / Antifreeze:

In today’s day and age, there are many variations of coolant/antifreeze and can be quite confusing. But they are all based on ethylene glycol (EG) or propylene glycol (PG). From this, six groups come out. Colors vary from types, to the different manufacturers.

1. Inorganic Acid Technology (IAT) – This is the old typical green antifreeze/coolant that contained Silicates, Phosphates and/or Borates. The average life of IAT was from: 2 years/30,000 miles to about 3 years/36,000miles (dependent on manufacturer’s interval specs).
2. Organic Acid Technology (OAT) – This variation does not contain silicates or phosphates. A version of this is called Dex-Cool that has been used in GM cars since 1996, and Volkswagen/Audi uses a similar version called G12, G12+ and G12++ of this antifreeze/coolant. They contain 2-EHA and /or Sebacate for corrosion protection. This is a long life coolant with an interval of around 5 years/50,000 miles (dependent on manufacturer’s interval specs).
3. Hybrid Organic Acid Technology (HOAT) – Is a combination of organic acid technology (OAT) with a low dose of silicates or phosphates. Most antifreeze/coolant is of this variation. This is a long life coolant with an interval of around 5 years/50,000 miles (dependent on manufacturer’s interval specs).
4. Nitrited Organic Acid Technology (NOAT) – Is an organic acid technology (OAT) that has no silicates or phosphates. It contains nitrates and/or molybdenum as part of their inhibitor package. This coolant is an extended life coolant and does not require supplements. This extended life coolant has a service interval of around 8 years / 750,000 miles (dependent on manufacturer’s interval specs).
5. Nitrited Molybdate Organic Technology (NMOAT) – This coolant is similar to NOAT that has nitrates, but also has Molybdate for diesel wet sleeve liner protection.
6. Poly Organic Acid Technology (POAT) – This a long life coolant that is propylene glycol based, organic acid technology. Currently Amsoil is the only manufacturer for this coolant.

Antifreeze vs. Coolant

Antifreeze – Is undiluted and must mixed to a 50/50 antifreeze to water ratio. Distilled water should be used to dilute antifreeze. Use the correct ratio recommended by vehicle manufacturer. As a note, running straight antifreeze in an engine, will result in a hotter running engine. Antifreeze does not have the heat transferring abilities as water.

Coolant – Is pre-diluted and ready to use. Coolant does not require water to be added

SCA (Supplemental Coolant Additive) / DCA (Diesel Coolant Additive) – Because additives in conventional (IAT) and hybrid organic acid (HOAT) coolants are consumed during the vehicle’s operation, they must be refortified with supplemental coolant additives (SCA/DCA) in order to maintain effective corrosion protection. On the other hand, OAT and NOAT coolants do not require SCAs. Also note that the inhibitor package does not determine the level of freeze or boil over protection; the inhibitor is responsible for corrosion protection only.


⇒Most antifreeze / coolants are dangerous to humans and animals if ingested. They can cause severe injury or death. Use caution with children and animals since most coolants are sweet tasting.
⇒Dispose of used antifreeze / coolant to proper recycling center.
⇒Wear personal protective equipment.
⇒Use caution when working with hot coolant.