I had my car checked and they said i need to change rear main oil seal ($1200), oil pan, CV boots broke and gasket change. I checked it by my self, software engr by profession, found that the only leak it had was from a broken gasket (Cam chain tensioner gasket and a broken pipe total $20) which fixed all the leaks. Their analysis was wrong. Also they will try to scare you by telling you to change that this etc.
Another story. They came to my home to sell$80 coupon for 5 oil changes. When i asked for full synthetic version, he said 10-20$ etc thats it. I bought it and now when i asked him how much it is, he said it is $120 for oil change with the coupon i have it will be 82$. The dealer charges only 92$ for this.
Basic thing. They are expensive, not competent and will try to cheat you. In all ways of business, they are bad.