Coolant for the car: finding the right one quickly and easily

In the automotive sector, customers often receive very good overviews of the right engine oil, transmission oil or brake fluid. However, when it comes to coolant, many do not come across any information that is all that helpful. Yet choosing the right coolant is just as relevant to the life of a car as the right engine oil.

What is the biggest problem in choosing the right coolant?

In a nutshell, the lack of an international standard for coolants is the big issue. Compared to engine oils, where a suitable oil can be determined based on its manufacturer-specific release or specification, coolant lacks such transparency.

Customers are inundated with a wide variety of colors, additives and special benefits. The primary question for every motorist is whether or not the coolant is at all suitable for his or her own vehicle. Once this hurdle has been overcome, a comparison based on the manufacturer’s own advantages would only be of interest. Returning to the search for the right coolant and the required quantity, clarity should first be provided as to what tasks a radiator antifreeze actually performs, what it is made of and how it is best mixed. These questions are briefly and concisely addressed below.


Task of the coolant

On the one hand, the coolant is responsible for lowering the freezing point of the entire liquid in the cooling system and thus preventing the radiator and all pipes from freezing. The real strength of a coolant therefore unfolds during the winter period, when at sub-zero temperatures the fluids threaten to freeze.


Requirements for a good coolant

A good coolant can quite simply lower the freezing point of water, but it must not corrode with the metals in the cooling system, attack rubber seals, or drive other signs of wear. So to be convincing in overall use, a good coolant must meet certain requirements:

  • Preventing deposits in the cooling system
  • Prevent foam formation
  • Improving corrosion and heat protection
  • Compatible with the metals and rubbers in the cooling system

Composition of a cooling liquid

The chemical components around monoethylene glycol (MEG), ethylene glycol (EG) or monopropylene glycol (MPG) are used as the basis of every coolant. Based on this base, the relevant additives are added to give the coolant the special property.

These additives include:

  • Corrosion inhibitors –So that the corrosion process is limited
  • Foam preventerTo prevent foaming during use
  • Stabilizers For consistent performance at extreme temperaturesn
  • Cavitation InhibitorsPrevents the formation of steam bubbles and thus pressure

The result of the basic components mixed with the additives is the coolant concentrate. This is ready for use in the cooling systems intended for this purpose.

OAT, IAT and HOAT coolant

As with engine technology, the individual coolants have also changed. Abbreviations such as OAT, IAT and HOAT are usually used to typify the type of coolant. They give an indication of which organic or inorganic acid is contained in the coolant whether they are miscible with each other.

IAT – The abbreviation IAT stands for “Inorganic Acid Technology.” It refers to the fact that inorganic acids are contained in the coolant. One such inorganic acid is silicate. Silicate was used at the beginning of coolant production. Concentrates with this acid base can be mixed with each other, but not arbitrarily with all OAT coolants (see the following table). For example, an IAT coolant is the G11 or G48 standard.

OAT – The abbreviation OAT stands for “Organic Acid Technology”. Here the reference to the use of an organic acid applies. In this case, silicate was not used. The first coolants with the OAT property were not miscible with the IAT coolants. However, further developments made it possible to mix OAT and IAT coolants. You can see which ones in the following table. An OAT coolant is for example the G12, G12+ or G30 standard.

HOAT – The abbreviation HOAT stands for a hybrid technology of OAT coolants. It stands for “Hybrid Organic Acid Technology”. The HOAT property combines the advantages of OAT and IAT coolants. Hereby silicate is used as corrosion inhibitor and all other additives are used by means of organic acids. This also gives them the property that they are miscible with all other coolant standards (thus also silicate-containing)! The HOAT coolants include the G12++, G13 and G40 standards.

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