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Auto Doctor: Flat tire repairs can damage tire pressure monitor

When a lessee fixed the flat tire on

When a lessee fixed the flat tire on her 2013 Hyundai Sonata, the "Low Tire Pressure" sign stayed illuminated on the dashboard. Credit: Hyundai

Dear Doctor: I'm leasing a 2013 Hyundai Sonata. I had a flat tire, which I had fixed with the silicone, but the "Low Tire Pressure" sign stays illuminated on the dashboard. All four tires are inflated properly. Will this hurt my fuel economy? Hyundai said if they look at it and the sensor is broken, I would be charged because the tires are not included in the warranty. -- Amy

Dear Amy: Go back to the shop that repaired the tire. If they took the tire off the rim, or if you drove the car with a flat tire, then the tire pressure monitor may have been damaged. I see a lot of tire pressure monitors damaged due to removal of the tire from the rim. You can go to any tire shop for a replacement tire pressure monitor. You'll have to replace the monitor before you end the lease or you may be charged the full retail dealer price.

Dear Doctor: Why does General Motors require the synthetic engine oil to be replaced so frequently? I only drive about 6,000 miles a year in my 2011 Chevy Impala, but my dealer wants me to replace the oil at 3,000-mile intervals. Can the oil get contaminated that fast with such short trips? I thought that the replacement intervals were doubled when using synthetic oils. Would this mean I'd be changing regular oil every 1,500 miles? -- Bill

Dear Bill: Oil change intervals are one of the most important services to prolong engine life. The oil change monitor does not discern the difference between full-synthetic oil and regular oil. The internal parts of today's engines require certain types of oil to properly operate. Unlike older engines, new high tech engines have a lot of electric and hydraulic valves and switching devices, especially camshaft timing valves and solenoids. The main failure for these control devices is contaminated oil. The dealer may be able to reprogram the oil change interval with the factory Tech 2 scan tool, however, I suggest changing the oil and filter twice a year with the use of full-synthetic oil. You should also drive the car on the highway weekly to ensure the engine gets up to operating temperature. This helps clean and burn out contamination and dry out moisture in the exhaust.

Dear Doctor: I have a 2003 Lincoln Town Car with a moonroof. When it rains water accumulates in the rear passenger floor. I've checked and it is not coming from the moonroof. Interestingly, my neighbor has the same problem. How do I fix it? -- Ralph

Dear Ralph: I find many leaks are caused from debris stuck in sunroof drains and heater box drains. To locate the water source in the rear seat floor area you'll need to have a repair shop to a water test over the roof, closely inspecting the rear window seals as well as body welds that may have cracks. This should not be a major repair.

Dear Doctor: I have been given conflicting advice on an emergency-only generator. I've been told to run it once a month and I've also been told to let it run out of gas and then store it. Should I use stabilizer? How long may I store 5 gallons of gasoline? -- Joe

Dear Joe: I live in an area that has frequent power outages and I have generators at my home and the shop. I keep gas in both of them and use gas stabilizer, too. I start the generators every other month and let them run for 20 minutes with a load, such as lights or any other power equipment. Draining the gas, however, can cause fuel-tank rust (if the tank is not plastic), the carburetor gasket to shrink and leak, and corrosion to form in the carburetor. You should change the oil in the generator one a year. If the generator is electric-start and has a small battery, then you should use a small battery charger and charge the battery every three months.

Dear Doctor: There are many new models with turbocharged engines offered today. My mechanic says to stay away from a turbo because they are not durable. I know this was the case in the past. Do you think the new turbo engines will be as durable as non-turbo engines? -- Fred

Dear Fred: Turbocharging is the wave of the future, as is supercharging. I personally own cars with supercharges and twin turbochargers. In the old days, turbo engines experienced poor oil lubrication. Also, oil would breakdown under heat in engines with carburetors. -- Junior Damato, Motor Matters

Junior Damato is an ASE-certified Master Technician. E-mail questions to Mail questions to: Auto Doctor, 3 Court Circle, Lakeville, MA 02347

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