You get better care dealing directly with a mechanic

It's essential to the longevity of your car - and the size of your wallet - to find a reputable auto-repair shop. And it's equally important, especially with today's technically sophisticated cars, to ensure that the work is done properly by competent technicians using up-to-date equipment.

Beyond the warranty period, new-car dealerships (as well as specialized automobile shops) can provide experience and familiarity with a particular vehicle model and year. They often take less time than general-repair shops and are usually good at correcting problems inherent in certain models, such as electrical devices that have annoying quirks. This could also mean smaller labor costs.

When it comes to the regular maintenance on your car, dealer back shops often do not have the best prices.

Also, in dealer service departments, as well as many franchised repair chains , the car owner is not able to talk directly with the mechanic. Telling the technician who writes up the service order exactly what you want done may be fine, but talking to the mechanic who actually uses the wrench is even better.

This can be an attractive aspect of using smaller, independent facilities where the customer deals directly with the mechanic.

Being able to communicate with your mechanic can save both of you a lot of work, time, and money. Once you have established a regular schedule of maintenance with one mechanic, he becomes familiar with your car, thus taking less time to work on it.

Andrew Diaz, vice-president of operating programs at the National Institute for Automotive Service Excellence (NIASE), recommends that car owners ''shop for a good repair facility just as you would for any other professional service. . . .'' Mr. Diaz says repair facilities should give a written estimate of the cost of work to be performed and that the better shops will guarantee their work.

After the work is done, question any charges that you don't understand. If you can't get satisfaction, go to the Better Business Bureau with your complaint.

If a mechanic is certified by NIASE, it can be assumed that he is qualified to do his job, at least the area in which he was approved. The institute offers a voluntary certification program for mechanics in major auto systems, such as engine repair, transmissions, front ends, and so forth. Ask to see your mechanic's credentials and make sure he is certified in the particular area in which your car needs repair.

The American Automobile Association (AAA) has a program it calls ''Approved Auto Repair Service.'' If a garage is approved, it meets the standards set by AAA, such as having state-of-the-art equipment, at least one certified mechanic, and clean facilities.

In a small town, finding a good garage can be just a matter of going to the one with the best reputation. But in the larger towns and cities, you'll have to search more carefully.

When looking over a prospective facility, check to see how the place is maintained. A disorganized-looking garage that has old parts strewn about the floor or oily rags hanging from the walls may well be unable to provide high-quality workmanship.

Obviously, you can't leave everything up to the mechanic.

Auto manufacturers and mechanics alike stress the importance of the car owner's role in maintaining his car.

It is crucial to the protection of your investment for you to make sure all preventive-maintenance schedules are strictly adhered to, whether you do the job yourself or have a mechanic do it for you.