OMAHA, Neb.-In a step toward greater acceptance, propylene glycol-based engine coolants-including the ``environmentally friendly'' Sierra' product manufactured by Safe Brands Corp.-have been approved by General Motors Corp. for use in GM vehicles, without affect on warranty coverage. In April, GM issued a service bulletin (43-62-01B) revising its previous position on the coolants. It stated that after a review of data supplied to the company, it had concluded that propylene glycol coolants that meet GM's performance specification GM 1825M may be used, and ``will perform adequately under most vehicle operating conditions.''
GM added that ``propylene glycol engine coolants may be recycled in the same manner as conventional ethylene glycol coolant,'' and no adverse effects will be encountered if these coolants are mixed prior to recycling.
However, GM further advised that prior to adding propylene glycol engine coolant to a cooling system, all existing ethylene glycol coolant must be removed. ``This can be accomplished either by utilizing water-based coolant flushing equipment or `waterless quick change' equipment. . . ,'' GM said. ``As with any coolant change procedure, be sure to thoroughly purge the heater core and block as well as the radiator before attempting to convert the system to propylene glycol coolant.''
Because freeze/boil point levels are different for propylene glycol and ethylene glycol, GM said ``it is imperative that coolants not be mixed. Removing all the used coolant. . . resolves this concern.''
Since its introduction several years ago as a safer antifreeze-coolant alternative that is less harmful to the environment, pets and people, Sierra has provoked a debate within an automotive industry concerned about its performance alongside the traditional ethylene glycol brew.
Joel Adamson, Safe Brands' vice president of marketing, applauded General Motors' new position, saying the company ``appreciates GM's painstaking and open-minded evaluation of Sierra's performance. It confirms exhaustive independent performance test results and the actual experience of consumers across the country.
``Since 1990, Sierra has been installed in over 1.5 million vehicles without a single performance problem being reported.''
Mr. Adamson said a 50/50 mixture of Sierra and water will protect a car's engine to a freeze point of -26 degrees Fahrenheit and will provide boilover protection to 257 degrees. ``Greater protection can be readily obtained by increasing the proportion of Sierra.''
Sierra is phosphate free, Mr. Adamson pointed out, ``and is much safer than conventional antifreeze-coolant formulations which contain ethylene glycol (EG).'' One teaspoon of EG antifreeze ``can cause a cat's death, less than two ounces is enough to kill a dog and as little as two tablespoons can be hazardous to a small child,'' he said.
Based in Omaha, Safe Brands was founded in 1990 to develop safer high performance automotive chemicals.