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Q: A friend of mine never changes the oil in his car. He has gone 70,000 miles without a change. He claims that oil never wears out. He cites a study of two New York taxicabs going 40,000 miles each. One had regular oil changes and the other none. Both engines were examined and there was no wear or tear on the cylinders and pistons on either. What are your thoughts?

A: Motor oil does not wear out. The additives wear out. What are those additives? Detergents, corrosion inhibitors, dispersants, oxidation inhibitors, viscosity modifiers, pour point depressants, anti-foaming agents and more. If I owned a crummy cab, I might not care, but I don't, so I change the oil in my vehicles on schedule.

Keeping it clean

Q: I live in the Mojave Desert, where we have wind and dust storms all the time. Our windshields are constantly dirty. By accident one day, I grabbed a Mr. Clean Magic Eraser Sheet and used it on my windshield. I couldn't believe how clean it got. No smudges anywhere. I then used the good, old microfiber towels to give a finishing touch. It also works great on all lights and chrome. My 2016 Buick Enclave shines like a new dollar.

A: This tip sounded so good that I had to try it. All I can say is: Wow. Tree sap and bugs came right off. I am also a big fan of microfiber towels for washing and waxing the car. They hold dirt between the fibers instead of on the fabric's surface.

Fuel lock is the key

Q: I park my car outside. I am concerned about someone putting something into the tank deliberately. Are locks available to prevent this? My Chevy dealer didn't have an answer.

A: Yes. They are called locking fuel plugs. Ford offers them. They are low-profile so as not to interfere with the fuel door.

Throttle issues

Q: I have a 2000 Dodge Ram 1500 with 100,000 miles. After startup, it sputters and misfires. The check engine light doesn't come on. I have changed the fuel pump, crankshaft position sensor and tuned it up. My local shop has been unable to find a solution. Any thoughts would be appreciated.

A: This type of problem often is due to a faulty throttle position sensor, but it also can be caused by a dirty throttle body. On a vehicle that age, have the throttle body thoroughly cleaned before you replace the sensor.

All shook up

Q: I bought a used 2005 Jeep Wrangler X. While driving on the highway, the front end began to shake violently at over 50 miles per hour. I googled the problem and found that this is called a "death shake." Is there any fix?

A: Jeep has released an improved steering damper. These are like shock absorbers that reduce oscillation.

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