Editors note: Bob Fria had graciously written many articles for the Pony Express during the course of his membership. Reprints of his articles will be published from time to time in future issues of the Pony Express for the wealth of knowledge he bestowed on us and as a remembrance of him and his contributions.

Is your classic’s cooling system long term protected form corrosion? Here’s new information you need to know. Water is the absolute best coolant for any engine. It conducts twice as much heat as glycol antifreeze, and allows engines to run significantly cooler.

However, all water is not created equal. There is an increased frequency of high levels of chloride in today’s tap water. Chloride is corrosive to aluminum and its alloys. San Diego tap water averages 83-127 ppm of chloride. AST D3306, (used by auto manufacturers), establishes the maximum allowable level of chloride for engine coolant at 25 ppm. Levels higher than this stimulate intergranular corrosion of aluminum/alloy radiators as it forms hydrochloric acid causing localized pitting.

Water softeners remove calcium, magnesium and certain other metal ions from tap water, but most do not remove chloride ions. Only Reverse Osmosis, (RO), membrane filtration can completely remove chloride from water. Fortunately now in supermarkets, RO water is found in gallon jugs marketed under the name “drinking water.” Any brand works. This is the water you should use to service your cooling system. Do not use spring water as it contains minerals for flavor. Distilled water because of its inherent instability, should not be used unless it is mixed with 50% antifreeze.

Modern day antifreeze becomes a big problem for some of our collector cars built prior to 1996 or engine blocks made prior to 1996. It’s an alloy problem. Today there are many different color antifreezes on the market other than the traditional “green.” They are NOT interchangeable. There are dramatic differences and cannot be mixed. Manufacturers don’t tell you this on their containers.

The newer colored types of antifreezes known as organic acid technology mixes, (OAT), contain carboxylates which cause problems in early pre-1996 engines. Insoluble gels form, gaskets may leak, damage to the radiator solder occurs and they require 5,000 miles of driving to form protective metal coatings.

Importantly, if used in these early engines, they cause the green inorganic acid technology, (IAT), surface coating to be worn away from these engines required to use green IAT antifreeze. Those stripped metal areas are not recoated by the OAT product and the process known as bridging occurs.

This means localized areas of coatings are worn away and neither IAT or OAT coatings are protecting. This causes pitting and eventually causes leaks and failure. The rule of thumb is whichever type your car came with from the factory, stay with it. Don’t be temped to mix or change types. Examples of early original types still found today at NAPA and other parts stores, (not PEP Boys and the like), are Prestone Heavy Duty, O’Reilly Antifreeze, Zerex Original Green and Peak Original Green. Follow these guidelines the next time you drain your cooling system and enjoy trouble free driving.

Happy Trails!

by Bob Fria Pony Express, Jan-Feb, 2015