Q. I have an SUV I plan to keep because I owe too much on it and don't feel like I'd get much in trade with current high fuel prices. It's fairly new, but what can I do to keep it looking good until the day arrives -- if it ever does -- when I can get a better trade-in because of lower gasoline prices? --E.H., Chicago

A. Car collector Larry Claypool of Frankfort's 'Vair Shop auto facility says most people will buy a car "in poor mechanical condition if it just looks good." That explains why many cars in mediocre or worse mechanical shape are routinely sold at car lots because the lot's dealer used a professional vehicle "detailer" to make them look good, at least temporarily. A car (or truck) thus should be washed every other week, no matter what season, and car wax should cause water to bead on body surfaces. No beads? Time for another wax coat. Also clean wheels and exterior plastics. The interior also should be regularly cleaned. "Any type of foreign material that sits on a vehicle's interior or exterior can alter the surface and lead to permanent damage, which can decrease a vehicle's value," says Mike Schultz, senor vice president-product development for Chicago-based Turtle Wax, a car care products producer. Also, keeping a vehicle garaged goes a long way toward keeping it looking good.

Q. Why should I change my car's engine oil? I have a friend who hasn't changed his car's engine oil in 30,000 miles and it runs fine. --J.F. Barrington

A. He seems like the person I knew who kept the same tires on his car for 85,000 miles -- and was shooting for at least 90,000 miles before he got new ones. Such people end up with flat tires or costly engine repairs. It all shows the amazing durability of modern engines and tires, although such tires become unsafe long before they're replaced and engines with such old oil use more fuel and don't run efficiently. The Car Care Council says clean oil is "the lifeblood of any engine" and found that 30 percent of vehicles failed because they had low, overfull or dirty engine oil.

Q. My car's left headlight has water droplets behind the lens. What can I do to get rid of the moisture? --J.W., Romeoville

A. The headlight typically has a two-piece plastic cover that cracks or loses its seal because of headlight heat -- and thus allows water leaks, says Elmwood Park's Caira Automotive. You must replace the cover, although that can be costly.

Q. I'd like to use what I feel is a more effective oil filter in my 2004 Chevrolet Monte Carlo. My dealer's service department just said it installs the filter that it's given. --H.W., Elwood

A. It's best to use factory parts because they're from the outfit that built the car. But make sure the dealer is installing such parts, which is usually the case.

Car question? Send it to Dan Jedlicka, Chicago Sun-Times, 350 N. Orleans, Chicago, IL 60654, or e-mail djedlicka@suntimes.com. Include name and hometown, and be sure to include a self-addressed stamped envelope to ensure a personal reply.