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Millington, TN (November 5, 2009) ~ Antifreeze mixtures that contain more than 50% glycol can cause overheating problems with fresh water cooled Indmar engines.  A consumer that is experiencing high engine operating temperatures or overheating at higher speeds and loads, may have too much glycol in the mix.  Other issues could also be the problem; water pump impeller, pinched hose, intake water obstruction, etc.

Indmar diagnostic testing has shown that mixtures with more than 50% glycol raised coolant temperatures.  As the mixture of glycol to water was increased, the risk of over-heating the engine was even greater.

What Happens When Mixture of Glycol Increases

Indmar uses Sierra propylene glycol for health and environmental reasons. Propylene glycol is as good, if not better than ethylene glycol. Some may argue the difference; however, there is no comparison when it comes to which is more environmentally safe.  For example, many animals like the sweet taste of ethylene glycol.  As little as a teaspoonful can be fatal to a cat and four teaspoons can be life threatening to a dog.  For more information and the benefits of using Sierra propylene glycol, go to .


It is evident that Indmar maintains an environmentally conscious effort in all of their processes from introducing CAT manifolds in their premium engines to all of the U.S. three years prior to regulations taking effect to using propylene glycol.   It makes sense why Indmar prefers propylene glycol in all of their closed cool engine systems…it’s cleaner, greener, and safer.

Indmar is the worlds largest privately held manufacturer of gasoline powered inboard marine engines. Indmar was the first marine engine manufacturer to bring EFI to the marine market and lead the industry when began to manufacturer catalytic converter – equipped engines in a standard production process.  Indmar takes pride in building marine engines for the long run manufacturing cutting edge, inboard power technologies that outperform and outlast competitive brands while providing a cleaner, greener and safer boating experience.  For more information, please visit .