Q. Our 2011 Ford F-150 extended cab pickup truck has a problem with the airbag light on the dash remaining on. The problem seemed to start after we adjusted the seat in order to put a child safety seat in the back seat. We have researched on the Internet and noticed a lot of other owners having this problem, not just with this certain year and style. How do we fix this? We have not gone to a Ford dealer yet. With all the other owners complaining of this problem, how would we set a recall in motion?

A. The first place to start is with a scan of the restraint system and reading the fault codes. When the light is on there will typically be a fault or error code, and that code can lead to a proper diagnosis and repair. The other issue is sometimes this can be normal. The SRS or airbag light can be on when the seat is too close to the air bag or when the weight sensor in the seat detects a low-weight occupant and shuts off the airbag to prevent harm to the passenger. Regarding filing a complaint go to www.nhtsa.gov to do so. 

Q. If I buy a five-quart jug of synthetic blend motor oil and use it over six months, would it be okay? How long can I store oil before it expires? 

A. This would not be a problem. I would only caution you to seal the container after each use. Many shops use oil stored in bulk containers, and this oil can easily be months old. According to various oil manufacturers the typical shelf life of unopened oil can be up to five years. 

Q. I noticed that the back passenger floor of my 2008 Mercedes C 300 was wet after it rained. I’ve seen YouTube videos showing attempts to fix this problem. Mostly, they try to unclog the drains from the sunroof. I’ve tried almost all possibilities to fix the problem to no avail. Most mechanics refuse to deal with this, and autobody places want to rip the interior out. I think car dealers should be held responsible.

A. Most water leaks are caused by clogged drains, leaky seals (doors and windows), and clogged air conditioner evaporator drains. I would start with using low pressure air and blowing out the sunroof drains. I would also look to see that the drains in the bottom of the doors are clear. If that doesn’t work, I would contact a few car dealers and see if they use a freelance leak detection technician. These air and water leak specialists know most of the tricks and locations of water leaks. Your 14-year-old car is well outside of any warranty and neither the dealer nor the manufacturer would be responsible for a water leak. 

Q. I own a 2016 Mazda CX-5 with over 100,000 miles. I recently took it to the dealer for a new battery and asked them to inspect the serpentine belt. To my surprise they said it looked fine. We take several trips a year and were hoping to get your thoughts on when to replace it.

A. We are seeing serpentine belts lasting well over 100,000 miles and even those that are 10 years old still look fine. If the belt shows no signs of glazing, cracking, or fraying, chances are it will be fine. For peace of mind, you should be able to replace the serpentine and water pump belts for less than $300 and have no worries on your road trip. 

Q. I have a 2005 Chrysler Sebring convertible that is shaking at 55 miles per hour. I have had the tires balanced four times but still have the issue. I switched front tires to rear and the shimmy moves from front to rear. One mechanic said to replace the shocks and also suggested that a wheel may be out of round. Any thoughts? 

A. If the shop that is balancing the tires can’t detect a defective tire or out of round wheel, it is time to find a new shop. Since the vibration moves with the wheels you at least know which wheel/tire is the problem. Since your car is 17 years old I would start by cleaning the backs of the wheels where they mount to the hubs. Corrosion can build up and cause the wheels to wobble. A good technician with a dial indicator should be able to look for problems and offer a solution. 

John Paul is AAA Northeast’s Car Doctor. He has over 40 years of experience in the automotive business and is an ASE-certified master technician. E-mail your car question to [email protected]. Listen to Car Doctor on the radio at 10 a.m. every Saturday on 104.9 FM or online at northshore1049.com.

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