CLEVELAND -- General Motors will soon pay millions of dollars to owners of some of its most popular cars and trucks.

It's the result of a long-running lawsuit over problems with many GM engines.

NewsChannel5's John Matarese reported that many GM owners will be getting a check as a result of one of the biggest automotive class-action settlements ever. It concerns the antifreeze inside millions of General Motors cars and trucks that's been blamed for expensive breakdowns.

Mary Ann Crabtree is one of many GM car owners who've discovered their antifreeze had turned to sludge, damaging gaskets, water pumps or radiators.

"They told us the coolant had gummed up. We had never heard of the problem or anything," said Crabtree.

Mechanic Al Duebber has repaired coolant-related problems on more than 100 GM vehicles since the automaker switched to orange Dexcool in 1995.

"What happens is they fail right in the journal here. And it'll cause coolant to leak out and eventually into the internal components of the engine," said Duebber.

Owners had to pay hundreds of dollars to fix their engines. Now, GM has agreed to a tentative settlement, agreeing to reimburse Dexcool repairs up to $800 for up to seven years or 150,000 miles.

It covers many 1995-2004 Chevrolets, Buicks, Oldsmobiles, Pontiacs and GMCs.

New GM vehicles no longer have this problem.

Owners should soon receive a claim form in the mail or can apply online for reimbursement.

If you want information about applying for reimbursement, call 1-866-245-4291 or applyonline.