Car "A" is stopped in a parking lot waiting to pull into a parking space. Car "B" is parked four spaces away. The driver of car "B" backs out of a parking space and strikes car "A" on the left rear portion of the bumper. Car "A" suffers damage and car "B" sustains none. What is the scientific explanation for why a stopped car suffers damage and the moving car doesn't? J.B., Oak Lawn

Seems you witnessed a demolition derby. For a scientific explanation, I will need the following information: the mass of both vehicles; the velocity and rate of acceleration of the moving vehicle; the year, make and model of both cars and their load, including groceries; powertrain equipment; type of road surface; angle of impact; ambient temperature; time of day; and weather conditions. Or, I can take a stab at it without that information-car "B" hit car "A" just right.

About a year-and-a-half ago, I purchased a 1987 Ford Escort from a Chevrolet dealership. I have had numerous problems with the car, but I'm at wit's end with one of them. The car loses about a half-quart of oil every 150 miles. Mechanics can't explain the oil loss. Just before Thanksgiving, I took the car to a shop for an oil change. Because of various complications, I couldn't get the car until Dec. 23. The next morning, I checked the oil level. The dipstick measured half full. I drove the car 9 miles after the oil change. What's going on? M.J.C., Chicago

It seems your car needs intensive care from a qualified technician. The oil is going somewhere. Oil doesn't evaporate at the rate you describe. Leaks and engine-oil consumption problems can be repaired. There are specific tests that can be performed to determine the cause of your loss. If a technician finds that a gasket or seal has failed, it should be replaced. If the engine is burning oil, that can be fixed, too. The extended mechanical maintenance policy you mentioned in your letter may pick up most of the tab for major engine repairs to cure oil consumption. As for replacement of gaskets and seals, the policy may not pay for the repair. Read the policy carefully and make sure the mechanic will accept the terms of the policy before authorizing repairs, or you might have to pay the entire bill. Or, you should find a mechanic who knows how to fill the engine with oil to its proper level.

The idle on my new 1992 Honda DX hatchback engine performs quietly and rhythmically but turns rough when I run the heater. Is this because operation of various electric-driven items intrudes on the computer's function? J.W.H., Downers Grove

You are partially correct. When you turn on the heater, the unit demands more power from the alternator. So, more engine horsepower is needed to turn the alternator. When that happens, you feel a change in the engine, which often is sensed as roughness. Actually, the engine is just working a little harder, and you feel the power pulses from it. To be sure everything is OK, ask an experienced Honda technician to check it out.

I hope you can settle an argument that's brewing between some young people and me. They read your column and believe it to be gospel. These young people let the engine run for 20 minutes before driving. I think that it's too long, and the engine will probably overheat. As a result of their practice, the car is giving them trouble. When it's really cold outside, how long does it take for an engine to warm up? What's your advice? V.M., Tinley Park

Hi kids! This is your Uncle Gizmo. After you read this, go clean your room, wash the car and tease your sister. There is no specific time in which a car engine will reach operating temperature. However, the engine will warm much faster if the car is driven. On really cold mornings, start the engine and let it run for a minute or two before driving away. Once under way, gently drive the car for the first few minutes. If the thermostat in the engine cooling system is operating correctly, heat should be felt from the heater a few miles after departure. If not, the thermostat may need replacement. Once you feel warmth from the vents, drive the car normally.

I read your column as soon as I'm finished with the Sports section. The 2.8-liter engine in my 1989 Pontiac Grand Prix stalls intermittently. I took the car to a dealer technician who ran all kinds of computer tests but couldn't find anything wrong. I drove the car a few days after the examination, but the car stalled again. After that, I took the car to an independent mechanic who cleaned the injectors, replaced the fuel and air filters and installed a new gizmo on the air intake. Then he tested the engine on a computer, which said everything was OK. I haven't had trouble since that work was done, but I'm afraid to drive the car. Can you give me some suggestions? J.D.K., Palos Park

Since the independent mechanic did his work, the car hasn't stalled. Because of that, I believe the car could be repaired. No one can restore your confidence in the car except you. The only way to accomplish that is to drive the car. If the engine should stall, a technician should inspect and test the throttle position, the crankshaft and mass airflow sensors.



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