Entrusting an $18,000 car to a teenager streaked with axle grease is, perhaps, a motorist's worst nightmare short of an accident.

Choosing a mechanic to keep a car in top running order is a difficult task for the average car owner.Everyone has heard horror stories featuring technical mumbo-jumbo like: "The chuga-chuga you're hearing is coming from the double-backflip overwhammy assembly. It needs a new razzenhelter and that'll cost you about 300 bucks."

Anxiety can be dispelled by making a few telephone calls, taking a quick glance on a repair shop's walls and asking some questions.

Before you take your car to an unknown fix-it shop, check with friends to see where they take their vehicles. It's best, obviously, to find someone with a car like yours - at least from the same manufacturer.

There are a growing number of repair "boutiques" specializing in a particular part of a car, such as the exhaust system, suspension or transmission. These can be a good bet for repair work.

After you've selected a shop, whether a specialty or a general repair one, check for certification of the business and the mechanics working there.

The American Automobile Association periodically checks the businesses it certifies, and mechanics can qualify for certification through the National Institute for Automotive Service Excellence.

A written certification is not a guarantee that a mechanic is competent, but it indicates that the technician has passed an examination.

Before work is performed, it's best to insist on a written estimate of the problem and its expected cost.

After the work is done, inspect the parts that have been replaced and have the mechanic explain what went wrong.

Finally, closely examine the bill to be sure that all costs - parts and labor - are itemized.