Q: In a recent column, a reader asked how cars know what the speed limit is. In addition to the GPS, my experience is that they can use the front camera to “read” speed limit signs. I know that my 2021 Ford Explorer does this because someone spray painted the sign in our neighborhood, changing the “30” into an “80” mph. My car read the speed limit as 80 until the sign was fixed.
A: Many vehicles now read the speed limit signs, but even some untampered signs are not right. You’ve probably driven on an interstate where the posted speed signs don’t agree with a GPS speed limit. Also, the signs may be hard for the camera to see in poor weather. Stick with the GPS speed.
Keep on schedule
Q: I have a 2024 Subaru Forester. I plan to keep it for many years. The Subaru dealer says the manufacturer recommendation is an oil change every six months or 5,000 miles, whichever comes first. I mainly drive short trips. At the first six months, the mileage was 2,195; the next six months it was 3,800. Do I need to get the oil changed every six months despite such low mileage? If I don’t, could that void my warranty?
A: Yes, neglecting the published schedule can void your warranty. That’s why I suggest that you always keep records of oil changes if you have them done somewhere other than the dealer.
Lots of air
Q: I have a ‘99 2-door Tahoe and run 265/75R16 tires. I’d like to buy a portable air inflator/compressor with a clamp style connection that I can keep in the truck. I’ve called a couple of the leading brands. Surprisingly, they’re noncommittal as to whether they have a portable one that will fill a tire of my size. Is there a brand/model that you would recommend?
A: Many inflators will work. You can retrofit some with a valve clamp-on device. Instead of a battery unit, opt for one that plugs into the vehicle’s power outlet (formerly the cigarette lighter). The best choice is a compressor that sits on the ground, not a handheld. You will need patience. These are large tires, and that means extra time to inflate them.
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.
