Q. We have a 2011 Ford F150 extended cab pickup truck. We have a problem with the airbag light on the dash staying 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 have noticed a lot of other owners having this problem. Not just with this certain year and style. How do we fix this? We have tried most of the solutions mentioned and still the light is on. We have raised the seat and played with the connections but have not taken the driver’s seat off yet and checked them. We have not gone to a Ford dealer due to the costs mentioned of those that have. Second question, with all the other owners complaining of this problem, how do we set in motion for a recall? This is a safety issue dealing with the airbag not functioning properly.

A. The first place to start is with a scan of the restraint system and read the fault codes. When the light is on there will typically be a fault or error code, 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 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 and then file a complaint. 

Q. I don’t know if you can help me but I’m desperate at this point. I noticed that the back passenger floor of my 2008 Mercedes’ C 300 was wet after it rained. On YouTube there are quite a few different cars that this happens to with all different attempts to fix the 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 auto body places want to rip the interior out which will cost me a fortune. I think car dealers should be held responsible. Any advice you can give me may help. 

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 the dealer, or the manufacturer would not be responsible for a water leak. 

Q. If I buy a five-quart jug of synthetic blend motor oil and use it over six months, would I be okay? With everything so expensive these days, if I see oil on sale, how long can I store it, 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 an unopened oil can be up to five years. 

Q. Hello doc I own a 2016 Mazda CX5 with over 100,000 miles. I recently took it to the dealer for a new battery and asked to inspect the serpentine belt, to my surprise they said it looked fine .We take several trips a year and was 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. Now for peace of mind for less than $300 you should be able to replace the serpentine and water pump belt and have no worries on your road trip. 

Q. I have a 2005 Chrysler Sebring convertible, I have 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 replace the shocks and maybe the wheel is out of round, I put two different tires on to test if it was the slipped belt, but it didn’t make a difference. 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.