Q: A friend of mine never changes the oil in his car. He has gone 70,000 without a change. He claims the oil never wears out. He cites a study of two New York taxi cabs going 40,000 miles each. One had regular oil changes and the other none. Both engines were examined and no wear or tear on cylinder and pistons on either. What are your thoughts?
B.F., Plymouth, Minn.
A: Motor oil does not wear out. The additives wear out. The base oil remains and is often refined and fresh additives blended in. 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 may not care, but don't so I change the oil in my vehicles on schedule. If you need more information, get in touch with a tribologist.
Q: I'm an 86-year-old female who reads your column all the time. I live in the Mojave Desert where we have wind and dust storms all the time. Once a year there's a sprinkle of rain so our windshields are constantly dirty. By accident one day I grabbed a Mr. Clean Magic Eraser Sheet and used it on my windshield. Wow, 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.
B.L., Mojave Desert
A: This tip sounded so good, I had to try it. Wow is right. Tree sap (actually honey dew) and bugs came right off. I am also a big fan of microfiber towels for washing and waxing the car. They hold dirt and grit between the fibers instead of on the fabric's surface.
Q: Thank you for answering the question of moisture in the fuel tank. 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 and I can't find one online. Thank you.
M.K., Des Plaines, Ill.
A: Yes. They are called locking fuel plugs. Ford has offered them for some time. They are low profile so as not to interfere with the door.
Q: I have a 2000 Dodge Ram 1500 with 100,000 miles. After start-up warm or cold, it sputters and misfires. No check engine light has lit. Have changed the fuel pumps, crankshaft position sensor and tuned it up. My local shop has been unable to find a solution. Any thoughts would be appreciated.