Coolant Performance

The required ethylene-glycol (antifreeze) and water mixture depends upon the climate and the vehicle operating conditions. The coolant performance of various mixtures follows:

Pure Water  -Water can absorb more heat than a mixture of water and ethylene-glycol. This is for the purpose of heat transfer only. Water also freezes at a higher temperature and allows corrosion.

100 percent Ethylene-Glycol  -The corrosion inhibiting additives in ethylene-glycol need the presence of water to dissolve. Without water, additives form deposits in the cooling system. These act as insulation causing the temperature to rise to as high as 149°C (300°F). This temperature is hot enough to melt plastic and soften solder. The increased engine operating temperature can result in engine detonation. In addition, 100 percent ethylene-glycol freezes at -22°C (-8°F).

50/50 Ethylene-Glycol and Water  -Is the recommended mixture, it provides protection against freezing to -37°C (-34°F). The antifreeze concentration must always  be a minimum of 44 percent, year-round in all climates. If the percentage is lower, engine parts may be eroded by cavitation. Maximum protection against freezing is provided with a 68 percent antifreeze concentration, which prevents freezing down to -67.7°C (-90°F). A higher percentage will freeze at a warmer temperature. Also, a higher percentage of antifreeze can cause the engine to overheat because the specific heat of antifreeze is lower than that of water.