[M.D. Holloway]

Extended Life Coolants (ELC’s) are long life products which have an inhibitor package which is more resistant to depletion and therefore does not easily deplete with time and provide over 4 years of service life. Extended Life Coolants are based on the Organic acid technology (OAT), or Carboxylate technology, which means that it contains neutralized organic acids as inhibitors. ELC’s do not contain Phosphates, Borates, Nitrites and Silicates. However most ELC’s still contain Glycol as Antifreeze.

Tolytriazole is an effective inhibitor for Copper and Brass protection. Sebacic Acid (sebacate) is a commonly used additive in organic acid coolants and provides corrosion protection for Lead and Aluminium alloys. Ethylhexanoic Acid is one of the primary inhibitors used in ELC coolants. It offers effective protection for ferrous components. Mercatobenzo Thiazole is a very effective inhibitor for brass and copper components

Pure Organic acid coolants do not contain any inorganic inhibitors such as Nitrites, Phosphates and Silicates etc. Hybrid or HOAT coolants have been developed to combine the advantages of extended service life of an organic coolant with the benefits of increased liner protection offered by some inorganic additives such as Nitrite.

Hybrid coolants are also known as NOAT or Nitrited organic acid technology coolant.
A Hybrid ELC coolant may therefore have all the organic acid inhibitors combined with Nitrite

As a general rule mixing of different type of coolants should be avoided as much as possible.
Even if the mixing of two different inhibitor technologies does not produce any adverse affects; their mixing will simply dilute the additive concentrations and reduce the long life advantages of ELC coolant. However, many ELC coolants manufacturers have declared their coolants as compatible with traditional coolants; as long as it islimited to occasional top ups. Examples are Caterpillar extended life Coolant. Majority of ELC Coolants and traditional coolants are not recommended by theirsuppliers as mixable with other brands.