How To

Is my car’s tire leaking or not?

John Paul, AAA Northeast's Car Doctor, answers a question from a reader who thought they had a slow leak, but was told they didn’t.

The Car Doctor answers a question from a reader who thought they had a slow leak, but was told they didn’t. AP Photo/David Zalubowski

By John Paul

July 8, 2025

5 minutes to read

Q. I brought my Honda Accord to the dealership because of a slow leak in the front passenger tire. I thought I might have gone over a nail, but the mechanic said there was nothing wrong. He did, however, say that the passenger front wheel was slightly bent. What do you think may have caused this, and is it safe to drive? There did not seem to be a concern by the dealership.

A. If you do not feel any vibration then the wheel is most likely fine and there is nothing to worry about. Wheels can be knocked out-of-round from a pothole or even bumping a curb. As for the tire leak, as good as new car dealers are with mechanical repairs, when it comes to tire issues I have had the best luck at tire stores. This is especially true when looking for very slow tire leaks.

Q. I replaced the battery on my old Dodge pickup truck, which went fine. What I did not realize was that my voltage regulator was failing. So, without realizing it I was cooking the battery, and it boiled some battery acid on the aluminum radiator. It caused a stain, white in color. I tried to remove it with metal polish including Noxon. Nothing works. Do you have any suggestion to remove the stain, or should I just try aluminum paint?

A. I have used Eastwood Radiator black for regular radiators. For aluminum I would start with a gentle cleaning with baking soda and water and then rinse and see how it looks. Then use some alcohol to remove any residue. You could also try commercial air conditioner coil cleaner if there are some stains on the radiator fins. The condenser cleaner is the product used for cleaning the condenser coils of a house A/C unit. Aluminum is self-healing and although paintable, personally I would leave that as the last option. Readers, do you have a better suggestion?

Q. I have a 2008 Toyota Corolla. Is the brake fluid DOT 3 or DOT 4? And if the fluid in the master cylinder is conventional, can I add synthetic fluid? Also, I have always read to only use brake fluid from a sealed container. So once the container is open, is the brake fluid okay to use?

A. When the car was new it was DOT 3 fluid, and you can use DOT 4 or DOT 5.1, but not DOT 5, which is silicone based. All brake fluid is technically synthetic since it is a blended manufactured product. DOT 4 has a higher boiling point than DOT 3, and DOT 5.1 is higher still; all are backwards compatible. What you would not want to do is use DOT 3 in a car that requires DOT 4 or 5.1 Again, do not use DOT 5 silicone fluid, which is not compatible with DOT 3, 4 or 5.1 fluids. As for the sealed container warning, brake fluid absorbs water. Water is the enemy of a brake system. You want to store brake fluid in a sealed container, not one that is open to the air.

Q. I own a 2021 Kia Seltos with 29,000 miles. My engine light went on one day and the very next day the car stalled and died. It was towed to a Kia dealership. My warranty ends soon. My car did have symptoms of a recent recall: intermittent stalling, and is now said to be abnormal oil consumption, but my car was not part of the recall. My car has been sitting on the lot for weeks waiting for approval from Kia to cover total engine damage from lack of oil. The oil light never came on to warn me of this. The Kia dealership claims they are going back and forth with Kia technical assistance for approval. I have sent proof of all my oil changes, so I have kept up with maintenance. The Kia mechanic told me that they are trying to make a case about how it was not serviced at Kia and the non-factory oil filter could have caused this issue. Just would like to know your thoughts on this and is this common for a company to try to get out of the warranty?

A. It seems to fit the criteria for the recall. Did the engine have a recall to have different sensing software installed? Most engines in the 2014-2024 period did. If that was not performed, then that may be an issue. Regarding maintenance, as long as you can prove the oil was changed at six-month intervals and the correct grade of oil and a quality oil filter was used, there should be no reason to deny warranty coverage. Recall or not, your car has a 10-year 100,000-mile warranty or 5 year 60,000-mile warranty. As long as you maintain it, the coverage should be intact. Regarding the oil light, the oil light measures oil pressure, not quantity, so it is not unusual the light was not on. Regarding the oil filter, the Magnuson-Moss law protects you. The Magnuson-Moss Warranty Act prevents manufacturers from voiding warranties or denying coverage simply because a consumer used a non-original part or had repairs done by a non-dealer shop, unless they can prove that the aftermarket part or repair caused the defect.

Q. I have a 2010 Toyota RAV4 with 116,000 miles and a 2019 Toyota RAV 4 with 20,000 miles. Neither car accumulates much mileage in the course of the year. I am no longer taking the 2019 to the dealership, as I have found a very reliable local garage that does the work for a fraction of the cost of the dealership. That being said, I try to self-maintain certain items, if I can, and the replacement of an air cabin filter would be one of them. I’ve read where they should be replaced on a yearly basis (or sooner if driving on very dusty roads), and with the beginning of the hot weather summer driving season, I would like to place fresh cabin air filters in each vehicle. What would be your recommendations? I have gone to Amazon, and of course there are many brands listed such as Puroma, EPAuto, Fun-Driving, Fram, Bosch, and Pure-Flow. Bosch and Fram seem to be double the price of others, and I am not exactly sure if that’s marketing or not. In any case, I would appreciate your thoughts as to which brand might be optimal for my two autos, which are driven mostly on local streets and highways.

A. I replace cabin air filters when they are dirty, not just on time or mileage. Toyota makes it quite easy to check the cabin air filter. The filter sits behind the glove compartment. Open the glove compartment and allow the door to fully open. You may need to move the stops to allow the door to drop down. Then the filter is located in a tray behind the glove box. Take out the filter if it is quite dirty and dusty, replace it. If there is only a little dust, pollen leaves, shake it out and reinstall it. As for brands, I prefer the factory filter, then WIX filter products and the newer Bosch HEPA filter. Readers seem to highly recommend Puroma Cabin Air Filter with Activated Carbon. I have not tried this filter, but even vehicle manufacturers are recommending these charcoal/carbon filters to eliminate odors.

John Paul is AAA Northeast’s Car Doctor. He has over 40 years of experience in the automotive business and is an ASE-certified master technician. E-mail your Car Doctor question to [email protected]. Listen to the Car Doctor podcast at johnfpaul.podbean.com.