I'm a mechanic

A MECHANIC has shared some insight on two sneaky auto store scams that can cost car owners hundreds.

Joe, a mechanic with 40 years of experience, has revealed some secrets about the inside world of auto repair shops.

The repairman, who wished to keep his identity concealed, told ABC News' 20/20 that some mechanics might try to squeeze more money out of customers by doing unnecessary jobs.

Joe stands by most mechanics, calling them honest, but many are pressured but their bosses to perform unnecessary repairs for a tiny profit.

“The shop has to stay in business. There are pressures to do things that maybe you wouldn’t do normally,” Joe told 20/20.

Joe said there is a special lingo mechanics use for questionable repair practice - one of them being a "wallet flush."

A "wallet flush" is where a routine oil change can evolve into something more expensive.

"An $18 oil change - well, they lose money on that," Joe told the outlet.

"The idea is to get you in so they can sell you the coolant flushes, trans flushes, power steering flushes - That's where the money is."

Another tactic is dubbed the "idiot light," which, according to Joe, is one of the most common and profitable ways to jack up a repair bill.

The scam works by exploiting fears over the check engine light.

"The check engine light will direct you to a failure code," he said.

"Guys kind of have the phrase where every code deserves a part."

Joe has shared some tips on how auto owners can avoid being ripped off.

"If you go to a shop, and they spring you up for all this stuff, go find another shop," he said.

Joe recommends getting a second option from friends, coworkers, or anyone else that owns a vehicle.

"Try to find a reputable shop that you can build a relationship with, and they will take care of you, and that's key," he added.

The simplest thing drivers can do is read the owner's manual of their vehicle.

"People don’t read the owner’s manual. They don’t know how to open the hood half the time," Joe said.

"I honestly don’t understand what they expect out of the car if they don’t know anything about it.”