What to do about stinky Sonata?

Q: I own a 2007 Hyundai Sonata that is in excellent condition with 100,000 miles on it.

I have been having this terrible odor in my car, especially strong when I get in it in the morning, but generally it is always there. I took the car in for a thorough deep cleaning and even asked them to check under the hood for any possible dead animal that might have crawled in there, but they found nothing.

The gentleman mentioned something about having the A/C filter checked because he said they can get moldy and cause an odor.

I'll have that checked out, but could it be coming from any other source? In the 11 years that I've owned the car I've never had this problem before.

Y.V., Milwaukee

A: Stinking microbes in the air conditioner housing are a common source of odors, but usually in the summer, not the winter. When it's cold, they are less likely to proliferate.

Many cars now have cabin air filters that must be changed regularly, and I suggest a filter with activated charcoal if available.

I would not rule out a mouse or other critter, though, as the culprit.

Q: Could you please explain how the temperature gauge works in cars? How can the outside temperature reading not be affected by traveling at different speeds on a very hot or cold day?

L.S., Chicago

A: Cars report the outside air temperature via a probe, usually near the front of the vehicle.

The reading is then sent to the readout inside the cabin. Notice that we said air temperature, not windchill temperature.

Automotive temperature readings are buffered, though, so that the readings do not swing so fast as to become confusing.

Q: I purchased a Subaru Forester in 2014 and drove it for 58,000 miles. It began using a lot of oil, more than you would expect it to and more than my 2006 Jeep Liberty with 138,000 miles on it.

I went to the dealer that I bought it from, and they gave it an oil change and sealed the engine so I could not tamper with it. They said to drive it for 1,200 miles, bring it back and they would check it. They also told me it was because I did not use their Subaru filters.

Well, I took it back and guess what? It passed. So about halfway through the oil change cycle, I needed a quart of oil.

Is 1,200 miles a real test or is it a ruse to get me to think that it is normal? I think they have a problem with the engine and are trying to avoid fixing it.

A: As far as car companies are concerned, one quart of oil every 1,000 is considered normal. Some engines do better than others, of course.

Keep in mind that some oil must be consumed during normal operation.

By the way, if a dealer demands that you use only a Subaru filter, the dealer must provide it for free, according to federal law. Otherwise you are free to use the filter of your choice.