Q: This past winter I added gas line antifreeze and water remover when I refueled my car. Is this really necessary since gasoline is 10 percent ethanol?

A: No, adding a gas line antifreeze is not necessary when using ethanol-blended fuel. The ethanol — ethyl or grain alcohol — is an effective antifreeze/moisture remover so no additional additive is necessary. In fact, adding a gas line antifreeze on a regular basis can be too much of a good thing — excess alcohol in the tank can cause driveability issues.

Q: I have a four-cylinder 2005 Hyundai Tucson I purchased new. It runs fine but the mechanic suggested changing the timing belt at the recommended mileage interval or spend three or four thousand dollars in engine repair costs if it fails. What are the symptoms of impending timing belt failure?

A: There’s the rub — there are no symptoms to impending timing belt failure. And since the 2-liter engine in your Hyundai is an interference engine — meaning the pistons can physically contact the valves if the timing belt fails — significant engine damage can occur.

Hyundai recommends timing belt replacement at 60,000-mile intervals under “normal” driving circumstances. Under “severe” service conditions, the replacement interval is 40,000 miles.

Q: I bought a 2013 Nissan 370Z last November. The windshield and rear window have colors like glitter in the glass. The colors are brilliant like rainbow or diamond. It is very distracting on a sunny day. I’ve taken the car to the dealer twice and they said they cleaned the glass with glass cleaner but the colors remain. Any suggestions?

A: Nissan recommends the use of 0000-superfine steel wool to remove foreign material from windshield glass. They suggest fresh steel wool from an unopened bag to avoid contamination that could scratch the glass.

The fundamental issue is whether the “sparklies” are in, or on, the glass. While foreign matter on the glass is not a warranty item, defective glass may well be. Have the dealer try the Nissan-recommended cleaning procedure. If this doesn’t “clear” the problem, ask them about warranty coverage for replacement.