Top 5 Car Questions That People Ask Mechanics

August 10, 2020
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When it comes to getting car help, there’s no shortage of things that owners want to know. And there’s no shortage of important vehicle-related information to learn. Start with the essentials. Take a look at five of the most common car questions drivers ask car mechanics — and their answers.

1. Why does my “check engine” light come on?

One of the common reasons your check engine light comes on has an easy (and free) solution. If your gas cap wasn’t put on tightly the last time you filled the tank, it can affect the pressure in the fuel-delivery system — and that triggers the check engine warning. Try tightening your gas cap first. If that doesn’t work, see your mechanic; it could be anything from a failing catalytic converter to faulty spark plugs to an oxygen sensor failure.[1] Because this light could indicate a number of different problems, it’s easiest to have your mechanic diagnose the issue.

2. What is the correct tire pressure for me — and how often should I check it?

The correct tire pressure varies from one car to the next. It’s important to know what your car requires because tire pressure can affect the safety and performance of your vehicle. You can find the manufacturer’s recommended tire pressure on a sticker that’s usually on the door jamb of the driver’s side. Always follow that number, not the maximum pounds per square inch (psi) number listed on the side of the tire itself.[2] Check the pressure at least monthly, or every time you fuel up.

3. Do I have to have my car serviced by the dealership to have it covered by my warranty?

The warranty on your car is good regardless of where you have it serviced. However, if you have car maintenance tasks, such as oil changes and tire rotations, performed somewhere other than the dealership, make sure you keep a record of when and where the work was done. Keep the receipts, too. If you have proof that the work was done, the dealership or automaker should honor the warranty.[3]

4. How often should I have my oil changed?

It used to be that drivers were encouraged to change their oil every 3,000 miles. Now, thanks to innovations in the way engines are designed and changes to oil formulations, that’s no longer the case. Today’s manufacturers typically recommend an oil change every 5,000 to 10,000 miles, and that’s also true if you’re using synthetic oils. Check your owner’s manual to find out what’s right for your car; recommendations vary by car make and model. The owner’s manual should tell you how often you need to change the oil based on the type you use and the amount of driving you do. This guide should also tell you what kind of oil to use.[4]

5. What should I check before buying a used car?

In addition to getting information about the car’s history via online reports, look for signs of failing parts, such as gauges and lights that don’t work properly. Rust, if it’s extensive, can weaken the car’s frame and make it unsafe to drive.[5] Check the electric door locks and windows to make sure they all work. You also want brakes that feel solid, not spongy. If the car’s exhaust system makes a lot of noise, this could be a sign of a big repair bill in your future.[6] When in doubt, have a trusted mechanic check out the car. Also, refer to these used car buying tips to help you make an educated buying decision.

While these may not answer all the questions you’d like to ask a mechanic, they’re five of the most commonly asked questions — and they can help you keep your car properly maintained.

If you are considering purchasing a car from a private seller, the “How to Buy a Car from a Private Seller” guide will provide steps on how to inspect the vehicle.


[1] “Is your check engine light on? Here’s 10 possible reasons why,” Digital Trends,, Aug. 31, 2019.

[2] “How Do I Find the Correct Tire Pressure for My Car?,,, November 17, 2019.

[3] “Do You Need to Service Your Car at the Dealership to Keep Your Warranty Valid?,”,, November 17, 2019.

[4] “How Often Should You Really Change That Engine Oil?,” Advance Auto Parts,, November 17, 2019.

[5] “Used Cars: How Much Rust Is Too Much?” CARFAX,, November 20, 2019.

[6] “What to Look for When Buying a Used Car,” Rainbow Muffler,, November 17, 2019.

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