Customer refuses to pay for oil change, demands mechanic put old oil back in: 'His truck might last another year at best'

It's always important to be weary when money is involved, and the fact that everyone has heard a tale or two about a scamming or dishonest mechanic adds to their apprehension when facing a service bill. The problem with thinking everyone is trying to get one over on you all the time is that you'll blame everyone for everything and find yourself constantly at odds. 

Typically, these types of demands from customers are a way of avoiding footing the bill or in the hopes that you might knock something off the top, counting on the fact that it won't be worthwhile to you to spend the time undoing the work you've already completed. It's a more common tactic than you might think and one anyone in mechanical servicing grows tired of pretty quickly… As a rule of thumb, mechanics are prone to strong reactions and have little patience for customers in the first place, so if you decide to go this route in your "negotiating," don't be surprised if your mechanic tells you to "jog on."

Still, while it's important to make sure the customer knows the expected costs upfront and is notified of any complications that are adding to that estimated quote. These disagreements don't usually go as far as the mechanic having to rip out their work and put the old (often faulty or worn) parts back—but it certainly can and does happen.