There's something about auto repair shops that two out of three U.S. drivers just don't trust, according to a new AAA survey.

The auto group reports that drivers complained about unnecessary repair services, being overcharged, poor workmanship and overall bad experiences with their mechanics.

Do you need a new mechanic? Here’s how to tell

“To minimize the stress associated with vehicle repair and maintenance, it is critical that drivers find an honest repair shop that they can trust with their vehicle,” said John Nielsen, AAA’s managing director of Automotive Engineering and Repair. “AAA found that one-third of U.S. drivers – 75 million motorists in total – have yet to find a trusted repair facility, leaving them vulnerable when trouble strikes.”

Is it time for you to find a new auto repair shop? We reached out to the pros at YourMechanic.com to help us identify some common red flags.

Here are 5 signs you need a new mechanic!

1. When a routine repair turns into something else

Did you bring your car in for an oil change and suddenly you’re faced with a big repair bill? It’s true that an inspection during an oil change could reveal issues with your suspension or timing belt, but you always have the option of getting a second opinion. If you choose to proceed, make sure that the mechanic clearly explains the problem and solution.

2. You didn’t receive an estimate

Your bill should never be a total surprise. After explaining the needed repairs, a good mechanic will give you a quote for what the job will likely cost you. Labor rates and methods of payment should be posted in the waiting room of the auto repair shop.

3. What training?

Does your mechanic know their stuff? The National Institute for Automotive Service Excellence is an organization that certifies mechanics and offers the ASE Blue Seal of Excellence. Look for mechanics who invest in their education by staying on top of trends, new certifications and industry news.

4. The customer doesn’t come first

Nobody expects an auto repair shop to be as clean as a hospital, but you also don’t want to spend hours in a place that’s a filthy mess. Is the staff courteous and helpful? That’s something to look for. You want to do business with someone who takes the time to answer your questions.

5. They don’t own their mistakes

After your car is repaired, the mechanic should show you the work that was done, including the replaced parts. You may also be provided before and after pictures. And if something goes wrong during the service or right after you get home, a good mechanic will work with you to make it right.

How to find a good mechanic

If you’re one of the 75 million drivers who can’t find an auto repair shop that you trust, AAA suggests that you start looking for one before an issue comes up.

Ask your family and friends for recommendations, and check the auto repair shop’s rating with the Better Business Bureau.