Over the years I have come across many engines that were very diluted on the ethylene glycol side. heat exchanger leaks etc. can cause this as can an owner adding only water when or if the EG level gets low.


Before winter be sure to test the ethylene glycol side of the cooling system. No winterization of an engine is complete without this simple test.


The Prestone testers, like shown, are dirt cheap and work satisfactorily for ethylene glycol (Prestone/Peak/Dex Cool type antifreeze). They can not however be used for propylene glycol.

Happy Boating!!