Q: I recently bought a Garmin DriveSmart GPS. I have a 2013 Subaru Outback. When the Garmin is mounted on the dashboard, it keeps losing satellite reception. When it is lying on the passenger seat, it works perfectly. Garmin support has no answer for me, and neither does the dealer. I think it has something to do with the windshield. A year ago I had the windshield replaced with an aftermarket one rather than an OEM. What do you know about this situation and is there a solution so that I can mount it on the dashboard?

C.H., Chicago

A: We turned to Nik Frye at Auto Glass Fitters for insight into aftermarket windshields. Frye said Subaru Outbacks have a heating grid attached to the underside of the bottom of the windshield. When activated, this grid heats the wiper park area of the windshield in order to melt ice and snow off the wipers when they are at rest. His sources agree that it is most likely the heating grid causing the interference. Try mounting the GPS directly to the glass, but higher up. And, if your windshield heater has an on-off switch, be sure to switch it off.

Q: I put synthetic oil in my 2008 Toyota to stretch the oil changes. But the dealer says that the 2008 model was not certified (I'm not sure that's the term) for synthetic oil and oil should be changed every 5,000 miles. True or false?

B.H., Center Valley, Pa.

A: We have never heard of a car requiring certification for any oil: synthetic, conventional or a semisynthetic (combination of both). Synthetic oil is superior to conventional oil and oxidizes less quickly, reducing sludge. That is why extended oil changes are permitted. However, we have heard of owners being denied warranty coverage if they cannot prove that oil changes were done in compliance with the published intervals. Your car is well out of warranty.

Q: I have a 2017 Ford Escape. My two side mirrors look cloudy. If you rub the mirror with a dry rag or your fingers the cloudiness goes away. It returns by the next day, repeatedly. The local Ford dealer did not have any ideas or suggestions. Mirror replacements are $150 plus labor. Any ideas?

R.C., Princeton, Ill.

A: Our first guess is that you park the car in an environment that leaves something on the mirrors. Moisture, for instance? If you think that new mirrors are the answer, you can buy replacement glass for a lot less than a complete mirror assembly for which the dealer may be quoting the price.

Q: The emissions test center could not communicate with the engine control module (ECM) on my 1998 Toyota Camry XLE. I was told that if trouble codes can't be read I will never get a waiver. I contacted four emissions shops and one dealer and they can't diagnose it. The ECM and harness are very expensive. My car runs great and has served me very well. Why junk a good working car and pollute the grounds of a junkyard?

S.W., Arlington Heights, Ill.

A: We really don't have any easy idea as to how you can pass the emissions inspection. But we do have an idea for an alternative. Sell the car. But be sure the buyer lives outside the area.

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.