My purpose here is not to make negative comments on the automotive repair industry, but to give my honest opinion.
I have worked in the auto repair business for many years and I have see many people get charged hundreds of dollars for a repair that should have cost a few bucks. I have seen techs put the parts they were being paid to install into their tool boxes and say the work was done. I've seen people who were told to replace parts that were not needed.
I have been fired from jobs for refusing to rush a job or lie about un-needed repairs. I have found through personal experience that thievery, overcharging, and incompetence are rampant in the auto repair business. That is the biggest reason I got out of it. I have found that chain stores are the worst. They seem to hire incompetent, inexperienced, greedy people and I recommend you stay away from them.
I have also met and worked for shop owners who were absolutely honest and competent. If you find one, stay with him and give him(or her) a good tip.
Good mechanics are hard to find and so are honest shop owners.Your best chance at finding honorable and honest mechanics is at the small shops who have been in business for a long time. An older shop with the owner's name on it usually has a good, honest mechanic or else he would have gone out of business years ago.
The best advice I can give is to know your car. Read the owner's manual and look it up on the web. There are forums for most models of cars and you can find out alot just by reading the posts and replies. Know your vehicle. Be aware that there are crooks out there who want your money and could care less about your thanks. Knowledge IS power. Especially for women, who are assumed to know less about their vehicles. Spend some time learning about the thing you use to transport yourself and your loved ones. Go to the links I posted about basic car care. Know what could be wrong and ask for the old parts back.
Take care of your car/truck and it will take care of you. Change the oil regularly, check the coolant/antifreeze, check all fluids, check the tire pressure regularly, and when you notice something wrong or different with your vehicle, get it checked out by your mechanic. Little things can become major things in a short amount of time.