Q About three years ago, the air-bag light came on in my 2005 Hyundai. The dealership fixed it, and the light remained off until the driver's seat was moved to accommodate a taller driver. The dealership again fixed the problem but told me that I would have to replace the air-bag system next time and that the air bags would not deploy in an accident if the light was on. Is this true? The light is once again on.

A When the air-bag warning light is illuminated, the supplemental restraint system -- the air bags -- is disabled. Hyundai and other carmakers warn against modifications or repairs to the front seats that could interfere with deployment of the side airbags built into these seats. So moving or remounting the driver's seat may be part of the problem. Ask the dealer or an independent shop to plug in a scan tool to read the specific B-series fault code or codes that have triggered the warning light.

Because the first problem with the air-bag warning light occurred before the seat was moved, the problem may be easily repairable. But be aware that the seat modification may make it more difficult to find a dealer or shop willing to do the repairs.

Q I have a 2007 GMC Yukon with 89,000 miles. I take good care of it and change oil every 3,000 or 4,000 miles. In the past year I have noticed that the "low oil" warning light comes on right around the time I am due for an oil change. There are no visible signs of a leak or burning oil. This seems unusual in light of the mileage. This engine switches between V8 and V6 mode depending on engine load. One mechanic told me that when switching back from the V8 mode it dumps the excess oil and burns it off. Is this true?

A This aluminum-block V8 engine has an engine management system that switches between eight and four cylinders. It does this by hydraulically preventing the intake and exhaust valves from opening and the fuel injector from delivering fuel to the cylinders that are being disabled. In the oil pan is a pressure relief valve that sprays excess oil generated by the cycling of the hydraulic valves that control the valve lifters. If this spray of oil is a bit excessive because of high engine speeds, clearances and wear and tear, it can lead to deposits in piston grooves that can "stick" piston rings and lead to higher oil consumption.

My Alldata automotive database pulled up GM service bulletin 10-06-01-008B, dated March 2011, outlining this potential problem. If oil consumption is less than 2,000 miles per quart, the suggested fix is to clean the pistons with a specific application of GM's upper engine and fuel injector cleaner and install a deflector around the pressure relief valve in the pan to control and redirect the oil spray.

Q I just purchased a V8 five-speed 2006 Mustang GT with 40,000 miles. I will be parking it in a dry, unheated garage for the winter. I am not sure what I need to do to be sure it fires up next spring without any issues.

A With such a new, low-mileage vehicle, not much. The basics: Fill the tank with nonoxygenated fuel and add SeaFoam; disconnect the battery and charge once a month or connect an automatic battery maintainer; make sure all routine maintenance like oil changes are up to date; inflate the tires to 35 to 40 pounds per square inch; toss dryer sheets throughout interior, trunk and engine compartment to discourage furry visitors; plug the exhaust outlet with a rag or tennis ball; spray brake rotors with a light rust inhibitor; check antifreeze for anticipated temperatures; open two windows just a fraction, and cover vehicle with a light, breathable car cover. Say, "Goodnight, sweetheart, we'll meet again next spring."