DETROIT-Aftermarket service shops may soon see orange antifreeze under the hoods of vehicles. Where did the green go? In some new vehicles it's been replaced by a new engine coolant formulated to last five years/100,000 miles-and that's three years/70,000 miles longer than conventional green coolants.
Texaco's Dex-Cool is ethylene glycol-based like other coolants, said Wayne Bradley, senior project engineer at General Motors Corp.'s Service Technology Group.
What sets it apart, aside from its orange color, is its inhibitor formula, which forms a film on aluminum surfaces and protects engine surfaces from corrosion.
Dex-Cool is being used exclu-sively by GM in some buildout 1995 models and all 1996 cars and trucks except Saturn and Geo.
Mr. Bradley said GM went to the extended-life antifreeze because studies show that customers want longer service intervals.
Research also found that many consumers change their antifreeze only every five or six years rather than at the manufacturer-recommended two-year/30,000-mile interval.
Other Dex-Cool benefits include enhanced water pump seal performance and heat exchanger protection, and longer service intervals.
Dex-Cool should not be mixed with conventional coolants, especially in vehicles that have been driven less than 3,000 miles, according to Mr. Bradley.
However, if the two coolants are mixed after the vehicle has been driven 3,000 miles, no immediate problems will occur, he said, but the service interval is reduced from five years/100,000 miles to two years/30,000 miles.
GM has taken several measures to alert techs and consumers that a vehicle has been filled with Dex-Cool: the coolant's orange coloring; underhood warning labels; and specific references in owner's manuals.
Mr. Bradley said service shops must learn about Dex-Cool so that they won't inadvertently top off a Dex-Cool-filled engine with standard coolant.
Dex-Cool may be used in older GM and non-GM vehicles, except those with high-lead solder radiators, he said.
Older vehicles can be filled with the new coolant, but vehicles with more than 3,000 miles will not benefit from its anti-corrosive feature, and the recommended service interval remains at two years/30,000 miles.