<prompt> Human: If I need to take my car in for routine maintenance, oil changes, tire rotations, transmission changes and such what are some things that shops will try and sell you that are really not necessary? For those of us unfamiliar with the inner workings of cars and most other machineryTo all those jumping to defend mechanics: I realized that there are many wonderful, talented and honest people in this industry, I was simply hoping to foster a discussion so that those who are, shall we say, less than mechanically inclined johnson bars and headlight fluid and such will not needlessly waste money when their cars need service. I think the general consensus here is that we need to take the car to someone who IS reputable, but the problem is finding them. Knowing which things are completely unnecessary can help to determine this, and find those good businesses out there.  <response>: Two best words to tell if theres BS or not: Show me. Watch out for neck-snapping levels of back-peddling when you do this. 