Coolant Performance: Notes

Coolant performance is measurable. For heat transfer, pure water absorbs 1 btu for each degree of temperature rise for each pound of water. This formula is altered when necessary additives to control boiling, freezing, and corrosion are added as follows:

• Pure water (1 btu/lbm °F) boils at 100°C (212°F) and freezes at 0°C (32°F).
• 100 percent ethylene glycol (0.7 btu/lbm °F) can cause an engine to run hot, cause detonation, and will freeze at -22°C (-8°F).
• 50/50 Ethylene Glycol and Distilled Water (0.82 btu/lbm °F) is the recommended combination that provides a freeze point of -37°C (-35°F). The radiator, water pump, engine water jacket, pressure cap, thermostat, temperature gauge, coolant sensor and heater are all designed for 50/50 ethylene glycol.

Where required, a 56 percent glycol and 44 percent water mixture will provide a freeze point of -46°C (-50°F).