Gorgeous do-it-yourself projects are around every corner of the internet. And with instructions that make it look so easy, anything seems possible. (All you need is a free weekend and a lot of patience, right?)

And, sure—sometimes it works, even if there are a few minor hiccups and the final product doesn’t totally match the picture. But when it comes to car maintenance and repairs, they’re almost always tasks for the professionals.

So before you put in your own elbow grease, learn from these car repairs you shouldn’t do yourself:

1. You want to change your own oil

The expectation: You change the oil in your lawnmower—so how hard can changing the oil in your car be? Plus, you already have the jack, the oil, the drain pan, the tarp, the wrench and the filter. That’s a recipe for smooth sailing, right?

The estimated cost: $35

The reality: Well, or so you thought. One minor slip-up, like not putting the oil filter’s housing O-ring in the groove, can have a major price tag. And that, friends, is something a trusted mechanic would’ve known to do from the start to prevent major engine problems.

The real cost: $3,500

2. You want to purchase a car that has performance modifications

The expectation: You found the car of your dreams, but it’s used. You do your due diligence by getting a Carfax report and hiring a third-party vehicle inspection company to inspect the car prior to making the purchase. The results? Two clean reports. Hooray!

The estimated cost: $200

The reality: A week later, there’s a burning smell coming from under the hood. You take the car back only to find a laundry list of problems: multiple engine oil leaks, thin brake pads, bad battery, unaligned steering … The computer system was put into service mode, so you—and the inspection company—weren’t able to catch onto these maintenance issues. However, a trusted repair facility would’ve caught it all prior to purchase.

The real cost: $6,000

Do you know when it’s time to replace your car battery? Here’s how to predict when it’s nearing its end.

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3. You want to replace your car’s stereo system

The expectation: Whether a speaker busted or you’re in need of new technology, it’s time for a new stereo system—and you found the perfect fit, touchscreen and all. So you make your purchase and decide to install it yourself. It can’t be that hard to unplug a few wires from the old system and plug them into the new one. Plus, there must be directions somewhere …

The estimated cost: $300

The reality: Well, it turns out it’s not that simple. Now, several dash lights are on and your power windows won’t go down. A trusted mechanic would’ve known that a bunch of other stuff can be hooked up to your car’s stereo, like sensors, backup cameras and steering wheel controls—just to name a few. Ouch.

The real cost: $90 to $120 just for an electrical system diagnosis—plus $1,000 or more for rewiring (depending on your car and what’s really wrong)

4. You want to fix a crack in your windshield

The expectation: It happens to the best of us—you’re driving down a highway when a rock ever so graciously hits your windshield, creating a small chip or crack. Bummer! But that’s nothing a small can of epoxy can’t fix.

The estimated cost: $10

The reality: Not only is the crack in your windshield still visible, it’s even bigger after that “easy-to-use” windshield repair kit. You should’ve called a professional—plus, that might’ve even been covered by your auto insurance policy. But now, it’s time for a completely new windshield.

The real cost: $300 to $500 (and much more if your windshield camera system needs to be recalibrated)

5. You want to install new brake pads

The expectation: People replace their own brake pads all the time, so why can’t you? You’ve done your research by finding the best how-to video on the internet, you’ve purchased the parts and, considering you’ve even replaced other parts on your car, brakes should be a piece of cake.

The estimated cost: $30

The reality: When setting out to replace your own brake pads, it’s easy to overlook one important detail—safety, not only for you but for others on the road. If you’re not a professional mechanic, there’s a lot of room for error that can cause dangerous circumstances. So, sure—some people replace their own brake pads, but it’s best to leave it to the pros.

The real cost: Beyond repair

Sit Back, Relax and Let the Professionals Handle It

Save yourself time and stress by asking a local AAA Approved Auto Repair Facility to make those car repairs you shouldn’t do yourself. Members get a free vehicle maintenance inspection, 24-month/24,000-mile guarantee on repairs and 10 percent off labor (up to $50).

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