Thursday, 17 August 2017 09:23

This information has been provided by Castrol

The increasing drive by OEMs to higher horsepower and torque engines, stresses engine and cooling system. This has led to the rapid expansion of the number and type of engine coolant products available for the customer to purchase coupled with increased demands of engine operators for longer service periods, greater component durability and engine life.

The increasing drive by OEMs to higher horsepower and torque engines, stresses engine and cooling system. This has led to the rapid expansion of the number and type of engine coolant products available for the customer to purchase coupled with increased demands of engine operators for longer service periods, greater component durability and engine life.Both heavy duty diesel engine and passenger car manufacturers are increasingly demanding the use of a Fully Formulated Coolant (FFC) containing ethylene or propylene glycol.

A FFC is made up of two parts:

  1. Glycol which aids in the heat transfer properties of the coolant
  2. A corrosion inhibitor package which aids in the protection of the cooling system components from corrosion, rust etc.

Commercially available coolants differ in the amount and type of glycol present and the types of corrosion inhibitor packages used. The amount of glycol is around 95% minimum for a concentrate or the stipulated level for a premixed, ready to use product for example 50% for heavy duty diesels and 33% for passenger cars.

The corrosion inhibitor chemistry used can be one of three types:

  • Conventional Additive Technology (CAT) coolant chemistry which uses only inorganic additives such as phosphates, borates, amines, nitrates, silicates etc.
  • Organic Additive Technology (OAT) coolant chemistry which uses mixtures of various fully neutralised organic (carboxylic) acids such as benzoic acid, sebacic acids etc with no inorganic inhibitor present or
  • Hybrid Additive Technology (HAT) coolant chemistry which uses a mixture of organic acids and inorganic additives.

Dangers of Mixing Coolants

There are different levels of compatibility for example, 2 products may mix together in a glass jar and look alright. The same 2 products when place in an engine and circulated for a day may still be ok.

However the same products when subjected to heat and stresses of the engine over 1 to 2 months may be totally incompatible.

Engine coolants are complex and finely balanced formulations of numerous chemicals. Most fully formulated coolants contain over half a dozen and often more different chemicals.

There are numerous corrosion inhibitors available to the formulator and not all of them are physically compatible with each other.

To add to the confusion, various engine OEMs have their own preference for particular inhibitors and will specify this in their various standards.The worst case scenario of mixing incompatible coolants is that some of the chemicals used can fall out of solution settling out as fine solids.

These solids can block fine passages in the radiator and cooling system, cause thermostats to malfunction and eventually cause severe and irreparable damage to both the engine and the cooling system. It is best to avoid mixing engine coolants. Do not add water to the engine cooling system when topping up or refilling the system, only add the correct mix of engine coolant with good quality water (distilled or deionised).

More Information

This information has been provided by Castrol.

Castrol has been supplying high quality lubricants to Australian workshops for close to 100 years and we are proud of our partnership with the MTA WA. MTA WA members can receive special offers from Castrol including 10% off your first order and special discounted prices for oils and fluids. Email This email address is being protected from spambots. You need JavaScript enabled to view it. or call 0400 192 921 for further details.

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