Ethylene glycol is the base for virtually all antifreeze. Propylene glycol is used to make environmentally friendly non-toxic antifreeze.
Traditional antifreeze uses Inorganic Acid Technolgy and has a limited service life. It uses silicates for corrosion protection
Extended Life Coolant uses some form Organic Acid Technolgy. (OAT) and is by definition silicate free. It has nothing to do with environmental concerns.
Hybrid Organic Acid Technology (HOAT) is an extended life coolant that combines OAT with silicates. It has a somewhatcreducex service life of 150K/5 years. Zerex G05 is an popular HOAT formulation.
Phosphates form deposits in the presence of hard water which is common in Europe and Asia so those OEMs specify phosohate free OAT formulations. It has nothing to do with environmental concerns.
Wet sleeve diesel engines suffer from cavitation problems that erode the sleeves. Nitrites and molybdate either in the base coolant or in the form of Supplemental Coolant Additives (SCA) are added to those formulations to fight the effects of wet sleeve cavitation. Cat ELC is one such diesel formulation.
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Kubota specifies an ethylene glycol Extended Life Coolant. That will be a silicate free OAT/HOAT formulation of some sort. It is not a traditional IAT silicate formulation.
ELC coolant comes in a rainbow of colors including green.
Dan