You are in the 21st Century , the era of the all knowing Internet. Customers are getting cyber smarter and Dumber, meaning if it is on the world web, it is the Truth/Gospel. Dealerships have a reputation, partially Fueled by aftermarket shops. { yes Guilty Here }. You have the power of that Trained to work on what the customer brought to your Dealership's Repair shop , that is your Claim to fame, run with that. Take the Time to explain things to the unknowledgeable customer, as we do here. Throwing around big words only pisses them off, at times.