Coolant (also known, rather confusingly, as antifreeze) is the water-based solution in an engine’s cooling system that is used to keep the engine from either overheating or, if you live somewhere particularly chilly, from freezing.
Flowing in a continual loop through the cooling system, the coolant is pumped through channels and pathways that surround the engine block where the cylinders and pistons are housed and draws heat away from the engine. It is moved on to the radiator where it is cooled and then is pumped back through the system once more.
Additives in the coolant, along with the pressurized nature of the cooling system itself, give the solution a low freezing point and a high boiling point. The coolant also contains ingredients that are designed to prevent corrosion, rust, and the build-up of scale – all of which could cause significant damage to the cooling system and engine.
WHICH COOLANT IS RIGHT FOR YOU?
There are effectively three types of coolant available: those with inorganic additives (known as IAT or Inorganic Acid Technology coolants); those with organic additives (known as OAT or Organic Acid Technology coolants); and those that are mixture of both (known as HOAT or Hybrid Organic Acid Technology coolants).
The colour of coolant was, at one time, pretty relevant to the composition of the solution, with green signifying an IAT coolant, red or blue an OAT coolant, and yellow and orange the HOAT coolants. However, while the colour was once a reliable marker of coolant type, this is no longer strictly true. This means it is important that an owner know, from composition rather than colour, which coolant is required for their vehicle. Automakers specify a particular type for their vehicles – there is no ‘once-size-fits-all’ solution – and different types of coolant should never be mixed.
The information on which coolant is correct can usually be found in the vehicle owner’s manual. Alternatively, a vehicle brand dealership will have the information. A qualified mechanic will also be able to help determine which coolant is appropriate.
WHAT IF I PUT THE WRONG COOLANT IN MY ENGINE?
Use of incorrect coolant can cause corrosion, channel blockages, mineral deposits and scaling within the cooling system, all of which can lead to some nasty damage to system components. Damage here will affect the ability of the system to perform properly and that can see the development of major problems. A severely overheating engine, for example, can suffer a cracked block – a very serious issue that will result in either a very expensive repair or the need for a replacement engine.
WHAT YOU SHOULD DO
Vehicle manufacturers spend a lot of time developing their products and testing them to determine what fluids, including coolants, should be used. It is always best practice to follow their recommendations and guidelines. Find out which coolant is recommended and stick to it.
WANT TO LEARN MORE?
MTA Queensland’s Vehicle Maintenance course is designed for those who are interested in gaining valuable information and learning good practices for everyday vehicle use. The result: a safer journey with fewer breakdowns and repairs. If you have ever wanted to learn how to carry out preventative maintenance, then this course is for you.
6 February 2020
Please note the information contained on this page is general in nature and does not take into account your specific needs or circumstances. You should consider whether the information is appropriate to your needs, and where appropriate, seek professional advice.