A man requests a "lube job." No oil change or other fluid checks, just a "good grease job." He leaves the car and says he will be back in a couple of hours. The technician assigned to the job raises the car and shoots grease into all of the available grease fittings, sometimes called "Zerk" fittings. Older cars used to have a dozen or more such fittings. New cars usually have none. The engineers have decided that their masterpieces will not wear out, so grease application is no longer required. This car had two fittings. It's a very easy grease job. The man picks it up and drives off. A few minutes later he comes tearing back into the driveway. "You didn't grease it!" he says, louder than necessary. "It still squeaks when I hit a bump!"
That is, of course, the first we knew about a problem with a squeak. We had not test-driven it, and without hitting a bump there were no obvious squeaks and this squeak was obviously not cured by either of the two available grease fittings. We were not surprised to hear this, because we know that most squeaks come from worn-out rubber bushings that cannot be greased, and modern cars have dozens of them. Why hadn't we test-driven it first?, he asked.
A car is left off at night with the key in the drop-box, with instructions to "align the front end." No phone number, just a name which was not in our customer file. We align the front end and wait for the owner to reclaim his car. As he is paying his bill he remarks that he was looking forward to a vibration-free ride now. The constant shaking had been driving him nuts. Whoops. We began trying to explain that alignment had nothing to do with vibration. Whatever had been vibrating would still be vibrating. We offered to diagnose for the vibration, but he was angry now. He felt that we were trying to pad the bill, and he just wanted to leave. His problem was probably tire balance. His parting shot was that we should have checked the tires for balance.
A lady brings in the family minivan with a directive from her hubby to have new spark plugs put in, nothing else. He would do it himself, but he can't reach the ones in the back of the engine. Looking at the car we recognize the problem. That model requires the removal of an engine mount to drop the engine far enough to reach the spark plugs. It's a tough job to do in your own driveway, so we take it on, and change the plugs for him. When the car is restarted, it has a miss in one cylinder. We diagnose it as caused by a faulty spark plug wire. It was apparently the problem the man was working on the whole time. He was angry that he had to pay for our labor to change the plugs when it was a problem with a wire instead. Why didn't we check the wires?
There is one answer to all three of the above cases. It is: "Because we were not asked to." In each of these cases, and hundreds more, the customer has done his own diagnosis, and has given instructions on how to repair the problem.
I think I have seen this work successfully, once, maybe. In every other case it would have been quicker and cheaper if the diagnosis was done by the professional. One big advantage is that the repairs are, therefore, guaranteed to cure the problem, (or they should be.)
If you think shops should automatically do things to customers' cars without being told to do so, let me tell you that is risky. One of my worst chewing outs, (chewings out?) recently was from a lady, as I was giving her a free ride to her home. She was mad because we had previously added a gallon of windshield washer fluid in her car, as part of a routine oil change. She had her own fluid at home, and didn't like having to pay us for ours. We had probably done that 5,000 times without a complaint from anyone, but that's no excuse to keep doing it. She said we should have asked first.
Let's see: if doing the same thing repeatedly and expecting different results is the definition of insanity, what would you call doing the same thing repeatedly and expecting the same results? Complacency? Hopefulness? You don't have to be crazy to work in this business, but it helps. I know.