Q: We live in the suburbs of Chicago and drive a 2015 Dodge Caravan, for which it's recommended to use regular gas rated at 87 octane level. We just completed a road trip to Seattle, and the gas stations in the western states showed the regular gas with an octane rating of 85. Do cars at higher elevations run just fine on the 85 octane rating? Could I have saved money by purchasing regular gas instead of midgrade?
A: At higher altitudes, the air is less dense. To maintain the air/fuel ratio, lower octane is acceptable. Modern cars adjust for changes in altitude and the driver never notices any difference in performance.
Open-door policy
Q: Regarding your recent article about car break-ins and the possibility of the thief using the garage door opener, I would guess that most car owners have a stand-alone garage door opener hanging on the sun visor, and it would be a cinch for the crook to open the garage door. My advice to anyone leaving their car in the driveway overnight would be to consider the door opener like another car key and bring it into the house overnight.
A: That's a good idea, if you have one of the older remotes that were the size of a deck of cards. But openers have come a long way since then — some can be programmed to operate up to four systems — and have gotten a lot smaller. There are many garage door remotes that are no larger than a key fob. They can be attached to your key chain or easily carried in a purse or even a pocket.
Limping home
Q: I have a 2008 Chrysler minivan. On my way home from work, I stopped to run an errand. When I started again, the engine was revving very high and I only had second and reverse gears. I had it towed to a transmission shop, and they said it was in something they called "limp mode." They said it was a broken shaft in the transmission and not worth fixing. When I picked it up, to my surprise, it worked fine. I have been driving it short distances for three weeks with no problems, but I am afraid to take it on a longer trip. Any ideas what the problem might be?
A: Various engine or transmission sensor issues, or even a brake system sensor malfunction, can result in the limp — as in limp home — mode. This is to allow you to drive to a safe place. The check engine light usually will glow, as well. Sometimes there is a temporary glitch that can trigger the limp mode. A technician can interrogate the vehicle's computer to track down the problem, fix it and send you on your safe and merry way.
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.
