Q: I have a 2014 Honda, and I am curious about the key fob. The battery must be at least 10 years old, and it doesn't look like they can be replaced. How long will it last? I hope it does not die sometime when I'm far from home.

A: There is always a way to replace the battery, but it's often not obvious. In your case, remove the emergency key by pressing the button on the bottom. Next, insert something between the top half of the fob and the metal part of the emergency key storage. Most fobs require a CR2032 button battery, but before popping the old one out, note the polarity. Replace the battery before it dies.

Fuel fix

Q: The owner's manual of my 2018 Subaru Legacy says not to use fuel that is more than 10% ethanol. Because E10 fuel is not available at nearby stations, can I mix half a tank of E15, which is readily available, with half a tank of pure gasoline to get, essentially, fuel that is 7.5% ethanol and therefore usable in my car?

A: E15 shouldn't be a problem for cars built after the 2001 model year.

Tire primer

Q: I recently purchased a preowned 2019 Lexus RC 350 RWD Coupe. All four tires are new, front 235/40 R19 and rear 265/35 R19. I had the front aligned and the tires balanced when I purchased it at a dealer, not Lexus. Recently, I took it to the Lexus dealer to have the oil changed and get a general checkup. The dealer wanted to balance and rotate the tires and do a four-wheel alignment, which I declined because I just had most of it done. Besides, my owner's manual states that front and rear tires of different sizes cannot be rotated. And what's the deal with four-wheel alignment?

A: Different sized tires on the front and rear axles should not be rotated. The industry standard is four-wheel alignments. The car is aligned to its thrust angle — the direction it points going down the road — which may differ from the straight-down-center of the car. Unless set to the thrust line, premature tire wear is certain.

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 motormouth.tribune@gmail.com.