Q: I bought a 2018 Ford Edge Sport new and have driven it for almost four years. The dealership said to use 87 octane gas, so that's what I've been using. My manual says I can use anything from 87 to 91. Where I fill up, 88 octane is usually a little cheaper. Would there be any harm to switching to 88 gas after all this time of using 87? Just trying to save a few dollars if I can.

A: Yes, you can switch, but you might not save as much money as you think. That 88-octane fuel is 15% ethanol and 85% gasoline. It is called E15. There is a slight fuel economy trade-off. According to the Department of Energy, you will likely get 4% to 5% fewer miles per gallon with E15.

Antitheft tip

Q: I'd like to weigh in on the recent discussion about thieves breaking into a car parked in the driveway in order to open the garage door. To avoid break-ins, I installed a wall switch between the opener motor power and my garage door opener switch on the wall. If you park in the driveway for the night, turn off the power for the opener. That way, it can't open.

A: Not a bad idea. Another option is to install a smartphone-controlled electrical socket adapter on the motor. You can deactivate and reactivate your garage door opener from almost anywhere.

Schoolwork

Q: My son is heading to college next month and will be taking his 2010 Infiniti EX35. The car will not be driven often, maybe the occasional trip to the store or to visit his girlfriend. Should I instruct him to take it out once a week?

A: Short hops might not provide adequate battery charging, so a solar smart charger might help.

Power trip

Q: I left my door ajar, leaving a dome light on, thus draining the battery of my 2007 Honda Ridgeline. I knew a jump-start would get me back on the road and allow the alternator to recharge it, but without another car available for a standard jump-start, I was stuck at home for hours waiting for my roadside assistance to show up. Can you recommend a portable battery jumper I could keep in my truck in case this happens again? I live in Las Vegas, where it gets ridiculously hot in the summer, so can said jumper be safely kept in my truck?

A: There are plenty of portable jump-start devices available both online and at your favorite auto parts or big box store. The desert heat shouldn't harm them, but, just to be safe, leave the power pack in your garage. When you are out and about, you should have no problem getting a good Samaritan to provide a jump-start, so a set of cables is all you need.

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.