Q: I have a 2016 Chevy Impala with 22,500 miles. I had a flat tire, and when I went to change it, I found at least 4 inches of water in the spare tire well. There were no indications of water on the carpet.

I found out that GM had a program bulletin on the car for a rear taillamp gasket seal that causes this problem. But the dealer will not correct this problem because no recall was issued. Customer care at GM said that if I get a repair invoice, "maybe" they will reimburse partial payment.

A: Unlike a safety recall, customer satisfaction repairs are not required by law. If you are handy with a screwdriver, you can replace the gaskets yourself. For about $20 you can get both gaskets. They have a peel-and-stick backing. If you prefer, any repair shop can probably do the job in under an hour.

Ammonia caution

Q: I use ammonia and water to clean house windows. It leaves no streaks. Is there anything wrong with using the same on car windows? Not only does ammonia clean quickly, but after the odor of the ammonia dissipates, all smells are gone. It cuts grease better than any other cleaner. And it's cheap.

A: Ammonia is a great cleaner, but I have one caution about using it on car windows: If they are aftermarket tinted, ammonia might harm the tint and, in some cases, damage the film.

A hot topic

Q: When something in the undercarriage of my 2012 Mazda 5 with 100,000 miles started rattling, I took the car in to the shop, thinking that it might be my exhaust system. The mechanic said it was a corroded heat shield and removed it. He told me that I did not need to replace it because "cars in the '70s didn't have them" and it wasn't worth spending the money to replace in an eight-year-old car because they "don't really do anything."

Although I was happy to not spend any money, I'm still wondering if this is good advice.

A: Cars in the 1970s didn't have a lot of things, so that isn't a valid argument. Heat shields started being installed beneath the catalytic converters because cars were catching fire when parked over dry leaves or tall grass. At only 100,000 miles, your Mazda is too young to be burned at the stake.

Up in the air

Q: I am tired of losing money in broken coin-operated air compressors at gas stations to fill my tires. Could you recommend a shop air compressor?

A: First, not all gas stations have coin-operated compressors. But all the ones in your neighborhood might, so let's move on to Part 2: I suspect that you want a compressor that you can plug into a wall outlet, not an industrial shop compressor costing $1,000. If so, they are less than $100 at home improvement stores.

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.