This specification covers the requirements for a recycled prediluted aqueous ethylene glycol (50 volume % minimum) base engine coolant and recycled prediluted aqueous propylene glycol (50 volume % minimum) base engine coolant for use in automobiles and light-duty vehicles. Committee D15 has developed this specification using experience, knowledge and research from recycling used aqueous base engine coolant and blends of used aqueous base engine coolant and virgin glycol. This standard does not apply to coolant produced from other glycol sources such as medical waste, distillation bottoms, airplane/airport deicers and polyester production waste. This specification provides a procedure for evaluating engine coolant recycling technologies through the recycling of a reference synthetic used engine coolant. It also specifies the chemical, physical, and performance requirements for the recycled prediluted aqueous glycol base engine coolant that is produced from that procedure. When used without further dilution, this product functions effectively during both winter and summer. This material is intended to provide protection against freezing, boiling, and corrosion in automobile or other light-duty service cooling systems. The values stated in SI units are to be regarded as the standard. The values given in parentheses are approximate equivalents and provided for information only. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.