Ten years after General Motors began using Dex-Cool as an antifreeze in most of its cars and light trucks, GM car and truck owners continue to complain that the coolant corrodes and clogs radiators and radiator caps, erodes water pumps, rots radiator hoses, causes chronic overheating and engine damage while leading to leaky engine gaskets.

Patricia in Barberton, Ohio, feels cheated by the automaker. "I have had 2 intake gaskets replaced on my 1997 Pontiac Grand Am. The gaskets cost me close to $1,000 and they told me there is no guarantee it won't happen again," she wrote in a complaint to ConsumerAffairs.com.

"I just recently saw about the Dex-Cool problems and that is what I have been using in my vehicle since that is the kind that is required from the automakers," Patricia said.

Dex-Cool is now used in almost 40 million vehicles sold by GM since 1996. On its website, GM claims Dex-Cool will last 5 years or 150,000 miles but a steady stream of consumers insist the product is defective and has damaged their vehicles.

GM is quick to clarify its confidence in the antifreeze by stating that the GM owner's manual recommended 150,000-mile service interval is not a warranty guarantee. On its website, the company now also warns owners to consult their vehicle "owner's manual for the type of coolant right for your vehicle" and never "mix one type of coolant with the other."

Lawsuits Pending

At last count there were 14 lawsuits filed in state and federal courts throughout the country by GM vehicle owners angered over their experience with Dex-Cool.

A Missouri judge may soon grant class-action status to suits in his state -- and that would mean that millions of GM customers could become involved in the lawsuit. The Missouri Supreme Court has declined to hear an appeal from GM challenging class-action certification.

The Missouri suit was filed in April 2003 alleging GM vehicles with Dex-Cool in their cooling systems developed a rusty sludge.

The plaintiffs claim that GM refused to repair their vehicles or pay for the repairs and the lawsuit seeks unspecified damages for breach of warranty under the federal Magnuson-Moss Act and the Missouri Merchandising Practices Act.

Samuel in Bellville, Ohio experienced a similar problem with sludge in the cooling system of his car.

"I have sludge in my coolant caused by Dex-Cool,' he wrote. "GM demands that the coolant be used. So far it's just the gasket that has to be replaced. I will see if further damage was caused," he told ConsumerAffairs.com.

GM Is Mum

GM will not comment on the pending lawsuits but continues to claim that Dex-Cool represents an improvement over traditional coolants. Nevertheless, the automaker has alerted mechanics that vehicles operated for 15,000 to 20,000 miles with low coolant levels "may be susceptible to the formation of a rust like material in the cooling system."

Deborah in Hornell, New York faced similar news from her mechanic when she took her 2002 Buick Century in for a maintenance check. Deborah was told the Dex-Cool needed to be flushed and refilled even though the owner's manual stated the coolant ought to be good for 100,000 miles.

"My car has only 48,000 miles," she wrote. "The Dex-Cool had corroded the engine and the mechanic also advised that the plastic manifold would need to be replaced since the Dex-Cool had literally eaten through it."

Deborah blames the costly repairs on GM because in her view the automaker "installed what they knew as faulty equipment, namely a plastic item in an engine unit and Dex-Cool antifreeze that does not work."

In Madison County, Illinois, a lawsuit claims Dex-Cool "began to turn into sludge which then accumulated in the vehicle's engine cooling system and radiator."

Clear As Mud

The bright orange coolant often changes into a muddy colored liquid and when the change occurs automobile mechanics blame Dex-Cool for expensive cooling system flushes, gasket replacements, and even new radiators and heater cores.

"You'll see heater cores leaking. You'll see frost plugs leaking. You'll see water pump failures. You'll see overheating problems. You'll see air conditioners not cooling very good. You'll see transmissions burning up at 100,000 miles if the coolant systems are not working right," said one mechanic who works on GM cars and trucks.

Ronald in Downey, California told ConsumerAffairs.com the Dex-Cool has almost destroyed the engine in his car. "The product in vehicles coolant systems deteriorates aluminum parts in the engine," Ronald said. "The intake manifold, cylinder heads and timing chain cover are all made out of aluminum. My vehicle needs all these parts replaced."

His problems worsened. "The motor has coolant in the oil and oil in coolant," indicating that the head gasket is leaking. "This is the second time this problem has occurred."

The repairs to his damaged engine have now cost Ronald more than $4,000 "because all the aluminum parts have to be replaced."

What To Do

As lawyers continue to collect names for potential class action lawsuits from people claiming Dex-Cool damaged their car or truck, automobile mechanics are advising that if you have Dex-Cool as a coolant in your vehicle, you should not replace it with another form of antifreeze.

If your car or truck came from the factory with Dex-Cool, you should continue to use that coolant both as replacement and to top off the radiator, the mechanics say.

Last but not least, if your car came from the factory with standard "green" antifreeze, don't switch to Dex-Cool.