strong>Dear Doctor: I got a 1998 Mercedes-Benz E320 with 45,000 miles three years ago. I only put about 1,000 miles on the car each year. The Mercedes has 48,000 miles. I use full-synthetic oil. Can I wait until the car reaches 50,000 miles in another year or so before I change the oil again? Marvin
strong>Dear Marvin: No. With the low miles on the 1998 model and the low usage of the car, I recommend an oil change once a year. Even though you are using full-synthetic oil there will still be buildup of acid and sludge -- and the lubricating parts are sitting in that.
strong>Dear Doctor: I own a 2005 Ford Freestyle 3.0L V-6 with 60,000 miles. The extended warranty expires at 75,000 miles. For the last six months when driving at 25 mph the engine feels like it has a misfire. What is causing this? Jane
strong>Dear Jane: A qualified technician will need to hook up a factory type scan tool and drive the vehicle. At 25 mph when the misfire is present, the technician can actually look at all engine parameters. Possible problems are early EGR opening, lean condition (lazy slow oxygen sensor), fuel pressure, injector spray pattern, or a weak spark.
strong>Dear Doctor: I recently acquired a 1990 Toyota Corolla with only 53,000 miles. It has been sitting for the last three years. I installed a new battery and the car started up. What should I do to service the engine properly? Manny
strong>Dear Manny: The only thing you need to do is have the engine inspected for normal scheduled mile maintenance, including the timing belt. If the Corolla is equipped with an automatic transmission, then I recommend the fluid be changed.
strong>Dear Doctor: I own a 1991 Cadillac DeVille with 104,000 miles. I had to replace the battery and started the car every other day. The battery went dead after a month. Why? RL
strong>Dear RL: The first step is to check the battery to make sure it will hold a charge. Secondly, any vehicle with a computer, or multiple computers such as your older 1991 Cadillac, will have parasitic current draw when the car is just sitting. Some vehicles have battery rundown protection to prevent this problem. If your car's battery has an abnormal current draw, then the technician will have to spend time with it to see where the draw is coming from. It could be from a relay switch, interior or trunk light, or faulty alternator to name a few.
strong>Dear Doctor: I own a 1994 Oldsmobile Cutlass with 92,000 miles. I recently had a $400 tune-up and the car also needed an ignition coil for $48. Now the windshield wipers only work when the left-turn directional signal is on. What could be the problem? Rose
strong>Dear Rose: The problem is in the wiper/directional switch. The technician will have to check all the connections before replacing any parts.
strong>Dear Doctor: I own a 1998 Ford Windstar 3.8L V-6 with 115,000 miles purchased used. My gas mileage is low. Would replacing the oxygen sensors increase the gas mileage? How many oxygen sensors does my minivan have? Pasquale
strong>Dear Pasquale: To check poor gas mileage a full engine running performance test and evaluation needs to be done. The technician will need to look at engine running temperature, fuel pressure, correct engine vacuum -- and a look at the spark plug color is also a must. Lazy upstream (in front of the catalytic converter) oxygen sensors will affect gas mileage. The downstream (in back of the catalytic converter) monitor the catalytic converter on most vehicles. And yours is one of them.
strong>Dear Doctor: What is your opinion on the 2010 Nissan Altima coupe with the four-cylinder engine and automatic transmission? Jimmy-John
strong>Dear Jimmy-John: The 2010 Altima coupe has grown up and looks the part as well as it drives. The four-cylinder engine is all it can be and does not make any excuses. Depending on your driving needs test-drive the 3.5L V-6 before committing to the four-cylinder.
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