The Data Speak for Itself...
The Petroleum Quality Institute of America (PQIA) is an independent resource for information and insights on the quality and performance of lubricants in the marketplace. Our mission is to serve the consumer of lubricants by reporting on the quality and integrity of lubricants in the marketplace.
Antifreeze/Coolant Terms and Definitions:
ASTM D3306 – Standard Specification for Glycol Based Engine Coolants for Automotive and Light-Duty Service
ASTM D6210 – Standard Specification for Fully-Formulated Glycol Based Engine Coolant for Heavy-Duty Engines
pH
The pH measures how acidic or basic a solution is. ASTM D3306 states the pH of an Antifreeze/Coolant should be between 7.5 and 11.0. While a low pH can result in corrosion on metal components and a potential for inhibitor instability, a high pH can also be of concern due to the potential to corrode aluminum and be an irritant to skin.
Freeze Point/Percent Antifreeze
ASTM D3306 states that when a coolant is diluted 50/50 it should have a freeze point of -33.5°F minimum. A high freeze point (low percent antifreeze) can result in costly damage to coolant lines and/or an engine block. A low freeze point (high percent antifreeze) can result in loss of heat transfer and the potential for cavitation corrosion and compromising the integrity of engine seals.
Glycolate & Formate
Glycolate and Formate are degradation acids formed by the breakdown of Glycols from thermal and oxidative conditions.
Chloride
ASTM D3306 states the maximum amount of chloride in a new coolant should be less than 25 parts per million (ppm). A high chloride level can be indicative of poor quality water and/or improperly executed system cleaning. A high concentration of chloride can be corrosive to engine components, particularly aluminum.
Sulfate
ASTM D3306 states the maximum amount of sulfate in a new coolant should be less than 50 ppm. High levels of sulfate can be indicative of poor quality water and/or improperly executed system cleaning. A high concentration of sulfate can also result in scale and corrosion.
Nitrite
Although nitrite may not be necessary to build a quality engine coolant, it typically is used for cast iron and steel corrosion protection.
Nitrate
Although nitrate may not be necessary to build a quality engine coolant, it typically is used for aluminum and solder corrosion protection.
Phosphate
Although phosphate may not be necessary to build a quality engine coolant, it typically is used for iron and steel corrosion protection. Phosphate can also be used as pH buffering agent.
Dentonium Benzoate (Bitterant)
Anti-consumption additive to make engine coolants unpalatable to people and animals. It is legislated to be in all ethylene glycol based engine coolants by certain states and/or municipalities. It has no measurable performance benefit or detriment to coolants at levels mandated by regional governments. Depending on state regulations, the range of bitterant is typically 30 - 50 ppm.
For more information on Bitterant and the 17 current states that require it within Antifreeze/Coolant, visit the like below:
http://www.hslf.org/news/press-releases/antifreeze-and-engine-coolant.html#.Vg1yMd9Viko