Q: I really appreciated your response to the non-seatbelt wearer! I wear my seatbelt all the time, but a number of months ago the driver's side seatbelt light/warning chime in my 2006 Pontiac G6 started going off while the seat belt is buckled. The shop said it would be $400 to repair because they would have to take the seat out to get to the area to repair. The chime comes on immediately after starting the car, then again about five minutes later and always chimes five times. The light illuminates several times while I am driving and the chime does, too.

A: From the symptoms you describe, the problem could be as simple as the seatbelt switch located in the seatbelt buckle at your right hip or its harness connector under the seat. Or it could be a more serious issue with the SDM (sensing and diagnostic module) or IPC (instrument panel cluster).

I would suggest having the shop unplug and test the seatbelt switch to determine if it's the culprit. I think this can be done without removing the seat. If the switch is bad, have it replaced. If the switch is good and a scan tool confirms the SDM is telling the IPC the seatbelt is fastened — yet the light/chime are still indicating the seatbelt is unfastened — the problem is in the IPC. You'll have to decide if it's worth this level of repair.

Because of the somewhat intermittent nature of the light/chime coming on, my best guess is the seatbelt switch.

Q: I have a 2014 Mitsubishi Lancer and was informed by the dealer service department that I need to use synthetic oil. I thought this was usually required for luxury or high-performance cars and an option for the rest of us. Do I really need to use synthetic oil in this car?

A: Without knowing which engine option is in your vehicle, my answer will have to be a bit generic. The maintenance recommendations from Mitsubishi call for API "SN" 0W-20 for their non-turbo engines and API "SN" 5W-30 for their turbocharged engines. Both petroleum-based and synthetic motor oils can meet these specifications, but why not use the best — a premium synthetic motor oil.

Q: I am curious what your opinion is about using only DexCool antifreeze in our two Buick vehicles as recommended by GM. An auto mechanic and auto body repairman with 30 years experience advised me not to use this product as he found it clogged up the heaters/heating systems in vehicles.

A: DexCool coolant/antifreeze utilizes an organic acid anti-corrosion technology and claims a much longer service life than conventional antifreeze that utilizes phosphate/borate/silicate anti-corrosion technology. Both coolants are ethylene glycol-based for their antifreeze capabilities.

Is one type better than the other? That question has been and continues to be heavily debated. The biggest issue is oxidation of the coolant over time and mileage. As long as the coolant level is properly maintained and the coolant is flushed/replaced within recommended intervals, both work well.

Q: I have a 2000 Buick Park Avenue. The driver's door refuses to open as easily as the others. It feels like there is a vacuum between the weatherstripping and the door frame. Please advise.

A: First, clean and lubricate the door seal/weatherstripping and seal area on the body with an aerosol silicone lubricant. If this does not help, perhaps the door has "sagged" on its hinges over the years and miles. A body shop may be able to realign the door for easier opening.

In the "old days" I used to do this by placing a piece of 2x4 below the hinges between the door and door frame and "push" the door toward close to slightly "readjust" the hinges.

If the hinge pins/bushings are worn, they can be replaced.