Domenic Disiena has seen a lot of car repairs that could have been avoided in his 35 years working as a mechanic. The longtime mechanic shows the engine of a Volkswagen Beetle to illustrate how ignoring your car can be a costly mistake.

"The young lady was driving the car with a check-engine light on for approximately a week. Now if she would have had the check engine-light diagnosed it would have told her its coolant," he said.

Instead the car overheated, the motor blew, and it'll cost $3,000 to $4,000 to replace it. Consumer Reports has spoken to automotive mechanics across North America who have equally scary and costly stories.

"Routine maintenance and early fixes when something starts to go wrong can save you plenty," Jon Linkov of Consumer Reports said.

For example, a transmission rebuild can cost you about $3,000!

"If your transmission fluid is too low, it's probably because of a leak," Linkov said. "If you do have to add fluid, don't overfill. That'll make it worse!

To prevent a full engine replacement -- a $3,000 to $6,000 job -- check your oil once a month.

"And remember to change your oil and the timing belt according to the maintenance schedule in your owner's manual," Linkov said.

And a catalytic converter can become overtaxed if your engine isn't tuned and starts to malfunction.

"So don't ignore that check engine light when it comes on, and make sure you get regular tune-ups!" Linkov said.

The bottom line is that dealing with car trouble early will spare you expensive repair bills down the road.

You owner's manual is really key to saving money because it will tell you how to properly maintain your vehicle, everything from when you should do oil changes and rotate the tires to more serious matters.

The manual will often tell you what the noises you might hear really mean. That can help you diagnose a problem before it becomes serious.

With a report from CTV British Columbia's Chris Olsen