Most cooling additive products tout claims of higher boiling point, reduced surface tension or improved lubricity but what does it all mean to you the consumer. We are hearing from our customers that their engine temperatures are reaching 240 degrees, 250 degrees and even 300 degrees and it is “okay” because there is no boil over. This may be a benefit to preventing coolant loss but is it good for your engine and its parts?
To understand why the chemicals are used in the cooling system you need to understand their purpose and claim. Increased boiling point is the most frequent claim. Raising coolant temperature helps prevents boil out and cooling system fluid loss. Sounds good, but lets understand the terms that get thrown around.
Specific heat is the amount of heat that it takes to raise the temperature of a standard amount of fluid a standard degree of temperature. Different chemicals have different specific heat. A fluid with a higher specific heat has greater capacity to absorb heat, which is a desirable property for a coolant. The specific heats of ethylene glycol is .57, propylene glycol .59 and water 1.0. Water has a higher tendency to gain heat and lose heat so distilled water is actually the best of all mediums to dissipate heat.
Latent heat is often confused with specific heat. When coolant is about to boil, energy must be added to change the state from liquid to or gas. This incremental heat is referred to as latent heat. For example a pound of water needs one BTU to get one degree closer to boiling point. But just at the boiling point, you need to add much more heat to push it over the top.
Surface tension and “slipperiness” of surfactant-based coolants is often claimed as a feature and benefit. The elements of water e.g. Hydrogen and Oxygen, carry a positive and negative charge. The polar nature of these charges creates a relatively strong bond between the water molecules. Absent air resistance and gravity, water tends to “clump” and forms a spherical shape. The geometry of a sphere has the smallest surface area per unit volume.
When water hits hotter spots of your engine it quickly heats to the boiling point and a water vapor is formed. Dispersing the vapor formation permits cooler fluid to contact the hot spot. Reducing the surface tension of the fluid permits the vapor to bind together and grow large enough and energetic enough to free itself from the surface.
We are frequently asked our opinion about various coolant additives. The best answer is found with the manufacturer who made the additive to understand what the chemicals are and what they do. That answer may not suffice anymore because some chemicals are impacting other products.
Pump failure it is often the result of a seal or a bearing failure. Seals exist to preserve bearings but seals are compromised by high heat, poor lubrication, contamination, corrosion, wear and age. A chemical which purposefully raises engine temperatures may not necessarily helping you shed heat from the engine but instead cause you to retain heat in the coolant. These chemicals may in fact impact the longevity of other engine parts e.g. a rubber seal or o-rings in your water pump.
FlowKooler cannot warranty pumps showing evidence of seal degradation due to high heat or chemical corrosion.
(The beaker image is courtesy of Horia Varlan and is licensed with CC BY 2.0)