| [GMCnet] Using DEX-COOL antifreeze [message #134844] |
Sat, 16 July 2011 15:57  |
emerystora
Messages: 4442
Registered: January 2004
Karma:
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Senior Member |
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Someone recently asked me if they could use Dex-Cool in their GMC. I told them not to use it and gave them the following information that I had once saved.
First, the cooling systems on all older cars have at one time contained traditional phosphate/silicate blends of antifreeze. Thus silicate and phosphate residuals will remain in the cooling systems and continue to break away from surfaces, crevices, and tight areas, entering the new DEX-COOL coolant solution. DEX-COOL is not designed to properly disperse or keep these materials in solution. Therefore, they will seek and adhere to the hottest surfaces within the cooling system, forming scales and deposits. Since the hottest areas are the locations where the greatest amount Of heat transfer takes place, they are the worst spots to have deposits that impede heat transfer. The result is a dramatic affect on cooling system efficiency and performance. Also since corrosion is most likely to occur under deposits, using DEX-COOL could affect long-term corrosion prevention.
The second problem with using DEX-COOL in infrequently driven vehicles concerns the completely organic character of carboxylates in DEX-COOL which make them very good long-life corrosion inhibitors. Unfortunately, being organic, they are consumed by some types of bacteria. The bacteria feeds off the carboxylates, using them as a nutrient, so the corrosion protection that they offer disappears and creates, a potentially serious corrosion problem. This is not a problem in daily drivers whose cooling systems regularly operate at temperatures of over 170 deg F., where the carboxylate consuming bacteria cannot survive. However, it is a problem in vehicles not driven regularly or stored during the winter months.
Finally, in some cooling systems, DEX-COOL may interact with internal materials. For this reason, a recent service bulletin from GM specifically states, “DEX-COOL may be used in 1994 and later Buick models for improved water pump seal performance. It should not be used in 1993 or earlier vehicles because its chemical ingredients interact with internal copper-soldered joints.”
The bottom line is that by using a carboxylate-based antifreeze such as DEX-COOL in a system that contains residuals from the old antifreeze, you could actually do more damage than good. The best approach is to use a traditional antifreeze, the type the system was designed to use.
ALSO, be sure to change your antifreeze ever two years. The anti freezing characteristics of the product are still go after two years but the corrosion inhibitors, antifoam agents, rubber swell additives and water pump lubricant contained in the original antifreeze will deplete over time. It might last longer than two years at times but play it safe and change it anyway at two years and you won't have problems with it.
Emery Stora
77 Kingsley
Santa Fe, NM
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