Q: My 2020 Toyota Sienna has a significant amount of corrosion on the positive battery post and absolutely nothing on the negative post. What causes this and is it problematic? Can it be stopped?

P.J., New Lenox, Illinois

A: It’s called galvanic corrosion and usually occurs on the cathode, the positive terminal of the battery. You can remove it, but it often returns. Clean the battery terminal and the cable clamp. Once clean, protect the terminal. There are commercial products available, but I like to use silicone dielectric grease. Battery terminal cleaning brushes are available at auto parts stores.

Q: What kind of battery does a 2016 Legacy Subaru need? Is an enhanced battery (and what is that?) necessary or beneficial? My husband and I love reading your column, Bob. We learn something every week.

S.A, Naperville, Illinois

A: I’m unclear on what you mean by an “enhanced” battery. I have a hunch you are referring to an absorbed glass mat (AGM) battery, the kind that cost more than traditional ones. AGM batteries’ acid is absorbed into a fiberglass mat instead of being a free-flowing fluid. No, you don’t need one.

Q: I have enjoyed your column since you first took over this column in the Tribune. I have learned a lot. For S.C. (who was seeking a solution for snow stuck in wheel wells), my suggestion is to spray the wheel wells with a lubricant designed for snow blower chutes. It should at least make the snow easier to remove, and road bumps may help dislodge it. Just a thought and keep the shiny side up!

D.K., Chicago

A: I wasn’t aware of such a product. Thanks.

Q: I have a 1999 Mercury Grand Marquis. Recently the fan control for the heat/AC only works on the highest setting. The lower settings are the same as off. Is this a complicated fix? Is it just replacing the switch, or could it be something more complicated and costly?

J.U., Park Ridge, Illinois

A: I find it exciting to answer a question about an older car where everything isn’t controlled by computers and their nodes. In this case, the culprit is most likely the blower resister, which drops the voltage to the blower motor for all speeds but high.

Q: We did so much research before buying our Nautilus. We are first-time Lincoln owners. We were attracted to all the bells and whistles, the bench back seat, large trunk, plus the idea that it is a hybrid. We have been getting regular notifications that the remote capabilities are not working due to a low battery. We took it in to the dealer, and we were told that it is because our phone and key fob are too close to the car (which is in our covered garage) and that it is constantly receiving pings/notifications. The key fob is probably 20 feet away, and our phones are 30 to 40 feet away. They also said we don't drive it enough.

L.Z., Evanston, Illinois

A: It seems to me that you were getting the bum’s rush. Contact the dealership service department and let them know that your problem persists. Tell them you are afraid of getting stranded. Ask them to provide a loaner vehicle so they can check out the problem while it is far away from your home, fobs and phones. If your car won’t start to drive it there, ask to be picked up.

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