If you live where subzero winter weather is common, old or improperly diluted antifreeze can be a time bomb waiting to destroy your engine.

"Anytime a cooling system freezes, that's the worst thing that can happen to it," says Randy Burns, owner/manager of Gordon's No. 1 Auto Service LLC in Franklin, Wis. "You could then end up dealing with something as simple as popping the radiator -- and that actually is the best-case scenario -- to a devastating situation of cracks in the engine block or cylinder head.

With the plastic end caps in many of today's radiators, the best outcome would be to have those parts crack, says Burns.

"That offers the freezing water a place to expand, and that radiator repair will run from $350 to $600, depending on the type of car. If the damage is to the engine, you're looking at replacing it with a new crate or rebuilt engine because it would be cost-prohibitive to track down and repair what cracked. That can cost more than $4,000," Burns says.

Prevention is simple and inexpensive. "Have your cooling system checked regularly, and flush and replace your antifreeze, according to the recommendations of your owner's manual," says Burns.