Motormouth: Thermostat could be the culprit in chilly Kia

Q: My 2011 Kia Sportage is trying to freeze me to death. When I first start out on a chilly day, the heater blows warm air as soon as the engine warms up, as expected. However, after driving for maybe 30 minutes, I no longer get warm air no matter how high I set the temperature or blower fan. The local dealer is baffled. My feet are numb. Any ideas?

E.D., Minnetonka

A: Heating issues are often caused by a malfunctioning thermostat. It isn't like the thermostat on the wall in your house. It is in the car's cooling system and prevents the water (coolant) from flowing through the radiator until the engine reaches operating temperature. Then, the thermostat opens, allowing the coolant to flow through the entire system, including the heater core inside the car. The thermostat then dithers to maintain the proper temperature. If it gets lazy or stuck, you won't get proper heating or, for that matter, cooling.

Q: Is it OK to add my leftover oil and gas mixture (50:1) from my outboard motor and string trimmer to my car's gas tank?

M.K., Chicago

A: It is rarely a problem as long as you are only adding a little fuel mix to a full, or nearly full, gas tank.

Q: Do premium fuels contain more detergents and other additives than regular? My little Ford Fiesta obviously doesn't need the higher octane, but it gets "heavy duty" use for short distances in dense urban traffic. Would extra additives benefit my car? Because I get gas only every 10 weeks, the extra cost of premium would mean nothing to me.

A: Nope. The major difference between the various gasoline grades is the octane rating. The additive package is usually the same across the board. To get the gas with the highest dose of additives, look for retailers who sell Top Tier gasoline. It contains more additives than the basic EPA minimum. Stop-and-go traffic does not constitute heavy use.

Q: I have a 2006 Buick Lucerne with 54,000 miles. Yes, I mostly drive it to church and back with an occasional highway trip. I had a motor mount replaced last April and since then have experienced a very noticeable vibration in the steering wheel. I have taken the car back to the repair shop three times and the mechanic, who has been very reliable, cannot find a cause. Please, if you have any ideas I would really appreciate hearing from you.

L.L., Chicago

A: Vibration in the steering wheel is usually caused by wheel imbalance. Chances are, the wheels were removed to do the motor mount job. If a wheel weight was accidentally lost, that could be the cause. Another possibility is that the wheels were installed in a different position of clock location than they were before. Finally, in some cases, the engine cradle may be out of alignment after the motor mount job was done.