Coolant Colour Confusion
We’ve noticed that there’s plenty of confusion in forums these days about the colour of heavy-duty coolants. Does it indicate anything about the chemical make-up of the coolant, or is it just a brand-to-brand thing? In this article, we’ll clear the air about this confusion, and help you understand the key requirements to ensuring the optimal health of your engine’s cooling system year in, year out.
To help answer your questions, we went to Head Chemist and coolant expert, Mike Hudson from Atmus Filtration.
First thing’s first, what does coolant do?
Put simply, the role of coolant is to transfer extreme heat generated by the engine, to the radiator, where it is expelled into the environment. It is then circulated by the water pump, back to the engine, to repeat the same process over and over again. Heavy-duty coolant also carries with it additives which prevent corrosion, scale and cavitation of the engine and its components, as well as providing anti-boil and anti-freeze properties.
Can I just use any old coolant?
If a quality coolant is not used, the risks to the engine include overheating, corrosion and cavitation. These problems can cause critical damage, leading to expensive repairs and equipment downtime, which consequently leads to lost revenue for your business.
What should we look for in a coolant?
First and foremost, choose a good quality coolant from a reputable brand and check that it has been tested to, and meets, a heavy-duty coolant standard. One such internationally recognised heavy-duty coolant standard is ASTM D6210, and coolants that meet OEM heavy-duty standards are even better. Premixed heavy-duty coolants typically contain a mix of 50:50 vol. ethylene glycol or propylene glycol and water, with 3-5% additives. In terms of the coolant’s properties, it should have good heat transfer abilities and a higher boiling point and lower freezing point than water. It should also prevent corrosion, scaling and cavitation, resist foaming, be compatible with cooling system component materials, be compatible with hard water, resist sedimentation, and be chemically stable. Other considerations include the service life of the coolant and its maintenance requirements.
Which colour coolant is the best?
The truth is the colour doesn’t mean anything!
In days gone by, the colour of coolant was determined by the types of chemicals used to prevent corrosion, meaning once upon a time, you could tell a lot about a coolant by its colour.
Older coolants that used Inorganic Additive Technology (IAT) were usually blue or green in colour. These types would normally have to be changed roughly every two years.
In the 2000’s came Organic Acid Technology (OAT) coolants, whose chemical make-up offered better protection for cooling systems, and extended the life of the coolant. These coolants were usually orange or red in colour and offered a minimum five-year or 160,000km change interval.
There are also coolants which are a blend of IAT and OAT chemicals, and these were therefore named ‘hybrids’ (HAT) and were typically yellow or green; but not always! Other hybrid technologies you’ll find are POAT (phosphated OAT), SiOAT (silicated OAT) and Lobrid (OAT coolants with low amounts of inorganic inhibitors), and these can be pink, violet, purple, yellow or orange.
Nowadays, we can’t rely on the colour to tell us about a coolant’s chemistry or performance. Coolant marketers and OEM’s have adopted their own tiered approach to differentiate their products, meaning the colour can no longer be used by consumer’s as a guideline to a coolant’s properties.
For example, PGPlus, a hybrid, lifetime coolant with 250,000km or 4000 hours service intervals, is dark blue in colour.
PG Platinum, an organic, lifetime heavy-duty coolant which requires no service thanks to its superior additive package, is red in colour.
Is there a legal standard for coolant colours?
These days, there’s no legal standard for a coolant manufacturer to use a certain colour, so it’s not easy to know what chemicals are in the coolant just by seeing its colour.
How should coolant be maintained?
Every brand of coolant requires different levels of maintenance. Some coolants, such as Fleetguard’s OAT coolant and PG Platinum are lifetime. Meaning they do not need to be changed over the life of the engine, others such as those containing nitrite used for cavitation protection, require regular additive top-ups, to replace additives that deplete over time. Fleetguard’s PGPlus is an example of this.
While some coolants are compatible with others, changing the chemical balance in the cooling system can be detrimental to its performance, so mixing different types of coolant is not recommended.
All coolants, no matter the type, colour or brand should be tested twice a year to ensure they are maintaining the correct chemical composition and concentration.
Shop our range of Fleetguard Coolants now!