Analysis kits for coolant and anti-freeze agents

As a leading laboratory, we analyse the quality of lubricants in Europe and the Far East and generate accurate diagnoses. As the fi rst laboratory in Germany to research coolant and anti-freeze agents, we are now offering our customers another completely new service. Aqueous coolants are essential for the safe operation of engines and many other systems. It is not without reason that leading engine manufacturers have drawn up detailed specifi cations for coolants and engine coolants. The regular checking of these agents is becoming increasingly important, and with the new OELCHECK analyses, everyone is on the safe side!


From now on, OELCHECK is also studying glycol-based coolant mixes and concentrates, frost and corrosion protection as well as heating and preparation water. To analyse these media, we have invested in additional test devices and installed our own water laboratory within our lubricant laboratory. Most devices used for water analyses are in fact also used for oil analyses, yet measuring methods and calibration are entirely different in this regard. Just as for oils, we have compiled special OELCHECK analysis kits for checking coolant and anti-freeze agents with which almost all practical- related questions can be covered. Modern coolant concentrates are mostly based on ethylene glycol and are free from nitrates, amino acids and phosphates. They contain a cocktail of special additives, with which they reliably suppress cavitation and are able to achieve the required long service life. In addition, they must be compatible with the up to 100 materials which can be built into a coolant system. Coolants ensure optimal heat supply and dissipation, protect against corrosion and cavitation as well as deposits and reduce freezing at sub-zero temperatures, and are used in motor vehicles, construction machinery and locomotives as well as in wind turbines and stationary diesel, natural gas and special gas engines. In order to ensure operability over a long period of time and therefore the safe operation of the cooled units, OELCHECK investigates all important parameters.

Table of contents

  1. Coolant state
  2. Water quality
  3. Decomposition products
  4. Contaminants
  5. Additives
  6. All-inclusive

Coolant state

At the start of every analysis, a visual evalutation of a sample takes place. Upon first inspection – which according to their specifi cation is usually a red, blue or green coolant – there are often signs pointing towards some contaminants, such as from dust or another coolant. The next step involves a refractometer and oscillating U-tube, which determine the refractive index as well as the density, both of which are measurements for the ratio of water and concentrate in the sample. If the normal mixture ratio of 1:1 is incorrect, frost protection can no longer be guaranteed. The pH value measures the acidity. Given that deionised water is mostly prescribed for coolants, pH-neutral water with a pH value of 7 is used as a rule. However, the coolant becomes slightly alkaline through the additives used in the concentrate. This reaction is desired so that the metals in the cooling system are protected against acidic attacks. Yet over time, the additives break down. If the pH value falls below 7, the water will become acidic and the cooling system may corrode. Measuring the pH value in the laboratory is therefore extremely important, as it determines whether the coolant still provides sufficient surface protection. If the conductivity of the coolant shows an increase in ions during the examination, it can be assumed that no deionised water was used during preparation. This is free from ions and therefore only minimally conductive.

Water quality

When assessing the water quality, everything revolves around the water hardness, hardeners and corrosion-inducing substances. The total water hardness is determined based on its calcium and magnesium ion content (hardeners or calcifiers). The higher the limescale content, the harder the water. The hardness is determined in German hardness degrees, or °dH. The preparation water must be softened, or otherwise softened in advance. If this is not the case, particularly when dealing with high temperatures, limescale deposits can build up which reduce heat dissipation or even block the cooling system. OELCHECK determines not only the water hardness and the magnesium and calcium content, but also checks the water for chlorides and sulphates. Compounds containing chlorine and sulphur should not be present in coolants as they can encourage corrosion or cause deposits.

Top tip:
As water quality plays an extremely important role, OELCHECK also analyses preparation water before use. Have a sample of this water analysed before mixing it with the coolant concentrate. It should only be used as preparation water once the OELCHECK laboratory has given the green light to do so.

Decomposition products

Much like oils, ethylene glycol and additives in a coolant break down during its period of use. Increased temperatures and air intake accelerate this process. Coolants oxidise, whereby acids form. Compounds such as acetates, formates, glycolates and/or oxalates are then documented in the sample.


Even when the coolant contains contaminants, deposits can form in the circuits. With a reduced or even a blocked flow, effective cooling is no longer possible. Attention should be paid to cleanliness and the high quality of the preparation water when filling a system, as insufficient water quality often occurs with limescale deposits. OELCHECK tracks its cause when testing the water quality. However, a coolant can also contain bromides, fluorides or metal elements, which are disseminated from the components built into the system and which affect its quality. When mixing two coolants, sludge deposits can form quickly. As a rule, coolant and heating circulation systems are not hermetically sealed. If dust enters during operation or fi lling, the silicon content increases. Yet silicon is also often present in coolant as an anti-corrosion substance. That is why OELCHECK tribologists consider carefully the value of silicon or silicate minerals when checking for additives.


Coolants generally contain a whole host of additional substances to ensure that they achieve long resting times and that the various metallic alloys in cooling systems are protected against corrosion. However, over time the additives break down and the coolant loses performance. It is therefore logical that OELCHECK also investigates the content of any remaining additives and draws conclusions from the resulting values concerning the reusability of the coolant.


It goes without saying that the OELCHECK analysis kits for coolants and anti-freeze agents are, like the all kits for oils and lubricating greases, all-inclusive. The kits are prepaid, and the price includes the costs for the complete analysis and diagnostics by an experienced OELCHECK tribologist. Within Germany, samples can be collected and dispatched at no cost using the enclosed UPS return slip. Finally, OELCHECK customers benefi t from free access to our customer portal,, which contains all results, as well as online sample entry and our technical hotline.


OELCHECKER Spring 2017, pages 4-5