Which Engine Coolant Should You Use?

Noria Corporation

"Since our plant is located in Miami, Fla., we are concerned with how our climate could be affecting our automobiles. In a tropical environment, is a corrosion-inhibitor coolant or a glycol-based antifreeze better for an automotive application?"

In tropical environments, the automotive industry may not have to worry about low temperatures, with only rare occasions of temperatures reaching below 50 degrees F. However, frequent precipitation and sunshine present other concerning problems for this type of climate.

Glycol-based antifreeze is constructed to enhance certain characteristics of water, such as lowering the freezing point, which raises the boiling point. A corrosion-inhibitor coolant is also extremely important in regards to corrosion potential throughout contact surfaces of the coolant.

Regardless of the climate, it is recommended that all engines use glycol-based coolants. Just because a particular environment may not experience freezing temperatures does not mean that other concerns such as boiling point, evaporation and cavitation should be ignored.

An automobile does not need to be in a hot environment to experience high temperatures that approach the boiling point of water. Rough riding, inefficient engine designs or even extensive direct sunlight can equate to boiling-point temperatures. Remember, the primary purpose of a coolant in an automobile is to alleviate the generated heat onto the engine block from the combustion chamber.

Inhibiting corrosion potential is a critical property of a coolant, and all coolants should have these types of inhibitors for a variety of reasons. Most antifreeze products on the market include corrosion-inhibiting additives, which are typically silicates and phosphates.

In addition, cavitation as a result of mechanical-induced pressure changes should be addressed with corrosion inhibitors such as nitrite and/or molybdate. These additives operate like a surface lubricant on metal surfaces to guard the produced bubble implosions from the pressure changes, which are most prominent in the water pump.

For tropical environments, glycol-based coolants or corrosion-inhibiting coolants alone may not be acceptable. Although both of these coolants have the required properties for sufficient temperature control of the engine block and other engine components while preventing internal components from experiencing the effects of degradation such as corrosion, an effort should still be made to ensure the coolant being used in arid, hot and humid climates contain glycol-based antifreeze with corrosion inhibitors in order to cover all of the bases.

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