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Q: The reader who was concerned about the disappearance of AM radio from cars should know that analog AM radio as we currently know it soon will be extinct, but there is an option for stations to convert to digital AM that was recently approved by the Federal Communications Commission (FCC). Some AM stations are using the HD FM format to transmit signals. For instance, in the Twin Cities, WCCO 830 AM simulcasts on 102.9 KMNB-HD2.

A: The FCC will allow U.S. AM radio stations to convert to all-digital HD Radio transmissions if they choose to do so. The FCC approved it effective Jan. 1.

A little extra oil

Q: Every time I have my oil changed, when I get home and check the oil level, it is ⅛ to ¼ inch above the full indicator dot on the dipstick. How does this happen? And does it make a difference to the engine, or am I just overly sensitive about it?

A: Being slightly over the full mark is no problem. One possibility is that the shop is in a hurry and does not allow the oil to fully drain to the last drop. Some of the old stuff might be lingering inside the engine, and that's OK.

A battery mystery

Q: Once a month, the battery on my 2014 Compass dies after not driving for a couple of days. Nothing was found when I left it at the mechanic overnight to monitor where it could be losing amps. This started happening about six months ago. I got a new battery, but something still drained it. Could the alternator be the culprit?

A: The alternator is an unlikely culprit. Are you leaving your key fob in the car? Leaving it on the seat could keep the communication active between it and the vehicle. If that doesn't do the trick, there probably is a parasitic draw somewhere else.

Just (don't) do it

Q: I have a Subaru Outback with AWD and 60,000 miles. The dealership keeps pushing me to change the front and rear differential fluids at a cost of approximately $185. The Subaru manual suggests only an inspection of the fluid, not replacing it. When I look online, the consensus seems to be that replacing the fluids might be a good idea. I usually follow the manufacturer's recommendation, but I am having second thoughts.

A: Businesses make money by selling things. That's why you're asked if you want fries with your burger. You can say no to both the fries and differential fluids.

Coming clean

Q: What's the best method to clean a dashboard and keep it that way as long as possible?

A: I asked friends what they use; Meguiar's Ultimate Interior Detailer, Griot's Garage Interior Detailer and 303 All Surface Interior Cleaner keep coming up. I tried each, and they all worked well. But there certainly are other good products that I didn't try.

Bob Weber is a writer, mechanic and ASE-certified Master Automobile Technician. His writing has appeared in automotive trade publications, Consumer Guide and Consumers Digest. Send automotive questions along with name and town to