If you own a car but your brain freezes up when you hear terms like water pump or serpentine belt, we know your pain. So do deceitful car mechanics who may take advantage of your naivete to push you to buy parts or services you don’t need.

That said the majority of mechanics are honest and straightforward. Even so, it pays to know how to approach having your car repaired so you don't pay more than your should. These strategies can minimize your repair bills — and even help prevent you from being swindled by a mechanic.

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Pre-shop around

Find a mechanic you know and trust before you need one, advises the Federal Trade Commission (FTC). Don’t wait until you’re broken down on the side of the road. Trying a potential mechanic for routine maintenance will give you an idea of what to expect if you need major work done. If a routine oil change cascades into an $800 tune up, you can be sure that a bill for a more complicated repair will grow exponentially too. On the other hand, if the mechanic alerts you to issues you may want to keep an eye on and is otherwise timely and affordable, it’s worth coming back to him when you need major repairs.

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Learn what parts really cost

It’s no secret that mechanics mark up the costs of car parts and apply them to customers’ bills. Even if your mechanic is transparent about this practice and tells you exactly how much extra he’s charging, it doesn’t hurt to shop for parts yourself. Mechanics get parts from a handful of vendors and tend to value speedy delivery over competitive pricing. Even if yours will sell you parts at his cost, you may be able to save some money by picking up major (and pricey) ones like radiators and alternators from a local auto repair shop. (Make sure you have the exact part name and model number.)

If you only need spark plugs or a fan belt, however, it’s probably best to let the mechanic use his own parts if he guarantees the labor for the duration of the part warranty. Keep in mind since mechanics are used to providing their own parts you should expect, and offer, to pay a higher hourly rate for labor if you bring your own.

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Steer clear of the dealer, with one exception

You might feel like nobody knows your car better than the dealer you bought it from — and that may be true. But such knowledge and training come at a price. In addition to paying higher hourly rates for repairs, dealerships typically use only original equipment manufacturer (OEM) parts. The makers of these parts are the same companies that built them when your car was brand new.

An independent mechanic will likely use some OEM parts as well, but he’ll probably use aftermarket parts as well, which are made by a different company but designed to match your vehicle, says the FTC. Aftermarket parts tend to be less expensive than OEM parts and often come with their own warranty. So it makes sense to go to an independent shop for out-of-warranty repairs.

One exception: if your car has a recurring problem that’s difficult to diagnose. An independent mechanic who can’t easily figure out what’s wrong with a car may simply “throw parts at it” — industry slang for replacing one part after another until the problem disappears. Obviously that’s a problem, because you’ll be footing the bill for the guesswork until the mechanic gets it right. A dealership probably has already seen the problem you’re having and can diagnose it quickly. What’s more, says the FTC, many dealerships charge a flat fee for diagnostics prior to completing repairs, so you won’t be paying for them to take their best guess. 

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Speak up

Most mechanics view repairs and maintenance differently than consumers. While we tend to think of a car as needing repairs only when something stops working right, a mechanic may be inclined to do everything needed to bring a car to peak operating condition. If you know that you want only the defect repaired, say so. Otherwise you could end up paying for lots of services that could wait or done elsewhere for less money. Even though it’s standard practice for mechanics to alert customers to any problems they uncover while they work, insist on a phone call before your mechanic does anything other than what you’re expecting. If you do hear from him, ask whether the new issue needs to be dealt with right away and what might happen it you do it later rather than sooner.

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Ask to view old parts

Performing unnecessary repairs is dishonest, but lying about the work entirely is worse. According to the FTC, one way to make sure you’re really getting what you pay for is to ask to see all the old parts once the work is done — but let your mechanic know you want this before you leave the car for repair. Asking beforehand sends a signal that you can’t be easily tricked.

Your mechanic may or may not agree to save old parts, but some states, including California and New York, have enacted laws that entitle customers to request any parts that are removed from their car during a repair. You certainly can leave them behind after you’ve seen exactly what was replaced. Certain new parts like air conditioning compressors and radiators come with a deposit called a core charge, which is designed to encourage consumers and mechanics to recycle old parts to get a return on the deposit. Some states require that you leave these parts with your mechanic, so request the right to inspect them once they’ve been removed and make sure your final bill reflects the deposit return. 

Paul Hope, a trained chef and DIY enthusiast, has restored two houses and writes about food and homes.