The word “coolant” is one most misleading word when it has to do with the cooling system maintenance. “Coolant” simply refers to a liquid that offers temperature-transferring qualities. It could be any kind of liquid. Plain water can be described as “coolant”. So be weary when you see the word “coolant” on a product, because it does not define its abilities accurately. Run a research on the product carefully to ensure it provides the qualities you want. If in doubt, do not use it.
Corrosion inhibitors are just chemical packages that should be added to soft or de-mineralized water. There are many basic formulations of corrosion inhibitors that are used and they have been around for many years. A good quality corrosion inhibitor will help in the control of:
- pH level (typically between 7.5 and 9.0)
- corrosion of all metals
- scale formulation
- cavitation erosion
N/B: Corrosion inhibitors have no impacts on the freezing or boiling point of the cooling system.
The biggest setback with corrosion inhibitor products is that they are not stable when in use for an extended periods and are not tolerant of hard water.
Anti-Freeze / Anti-Boil (AF/AB) Concentrate
AF / AB concentrate is often recommended to be used between 33.3% and 50% by volume in Australia. The main merit of AF/AB is that the glycol component increases the level at which the system will boil and decreases the level at which the system will freeze.
In summary, all corrosion inhibitors work better when blended in glycol as it gives better stability for the corrosion inhibitor chemicals. In recent years the use of AF/AB has become the choice of manufacturers to stop the incidence of “hot spot boiling”. This phenomenon generally happens where the coolant comes close to the exhaust ports of the cylinder head. Steam pockets occur and, of course, heat will not pass through steam, hence the term “hot spots”. The results can be catastrophic to cylinder heads and gaskets.
MODERN VEHICLE LOADS
Cooling systems of modern cars work harder than those of the past. It is of great importance to maintain them correctly. Remember, there is no such thing as a product that will end corrosion completely. At best, it can be kept under control with care and selection of the right protection products.
VEHICLE MANUFACTURER RECOMMENDATIONS
If a manufacturer recommends AF/AB to be used in their vehicles, then you have no choice. You may reason “but I’m not going to the snow”. Climatic conditions however are only one of the reasons for a manufacturer to specify AF/AB; refer to “hot spot boiling” in point 3 above. It can be potentially dangerous to change from AF/AB to an inhibitor if AF/AB is the recommendation of the manufacturer. On the other hand, there is no problem with changing from an inhibitor to AF/AB after a flush.
Sadly, too many people think a cooling system starts and finishes with the radiator. Nothing could be further from the truth as a radiator is the easiest cooling system component to repair or change. Modern cooling systems are smaller, lighter, have to dissipate higher temperatures and are made of more complex metal alloys. Proper maintenance is required to ensure long life of cooling system components and efficient engine operation. Bear in mind that the average cooling system circulates around 6,000 litres of coolant per hour at 60 km an hour.