Q. My friend has a 2004 Chrysler Pacifica with 75,000 miles on it. The problem is that it is using oil. The last time the oil was changed the mechanic told me the engine was at least a quart and a half low. The previous time the oil was down 3 quarts. The service manager told me that oil consumption is common in Chrysler products. What do you know about this?

A. Any internal combustion engine uses some oil during its normal operation. Most engines are considered normal if the oil consumption is less than one quart in 1,000 miles. If your friend changes the oil in the Pacifica every 4,000 to 5,000 miles, it is acceptable for it to use two to three quarts of oil between oil changes. At this point, I would check the engine for oil leaks, have an oil change performed using the correct grade of oil and check the oil every 1,000 miles.

Q. My 2003 LeSabre has developed a growl heard only when the car is moving. It increases in pitch as the velocity of the car increases on the highway. I had both of the front wheel bearings replaced; the mechanic found both dry and rusty. However, even with the new bearings, there is still a growl. Why?

A. The growl could be worn rear wheel bearings, axles shafts, cupped or scalloped tires or perhaps a bearing in the transmission is starting to fail. At this point, the technician will need to isolate the location of the noise. Running the car on a lift or dynamometer may help or using a tool such as the “Chassis Ear” may pinpoint the noise.

Q. I own a 2002 Elantra. I have noticed lately that the rear defrost is very slow. It takes a good 15 minutes to clear the back window. Does the rear window need to be replaced or is it simply a fuse problem?

A. The first place to start with any electrical problem is with the power supply. If it has been determined the fuse and switch are okay, then the grid itself may be damaged. A technician will measure voltage across each line of the grid. It is possible that one of the lines of the grid have failed. In some cases the repair can be performed inexpensively with a repair kit. These kits contain a conductive paint to repair grid breaks and special adhesive to repair electrical tabs.

Q. We own a 1998 Volvo S70. The car has 136,800 miles and runs well with the usual fixes and adjustments that can be expected for a car of this age. While most issues can be addressed, we have recently been having a problem, which we cannot seem to fix. Our headlight illumination has been getting less and less bright, and we now use our high beams for regular night driving with nary a flicker of the oncoming headlights to indicate that our high beams are bothering these drivers. This, of course, means that while we are doing our normal night driving with the high beams on, we effectively no longer have high beam lighting when we need it. We have tried cleaning the lenses with a special solution, but this has not worked. Is this a common problem? Do you have any suggestions for what we might do?

A. The first item that needs to be checked is the voltage to the lights themselves. If the voltage is less than specification, the bulbs will be dim. In addition, Volvo has had several issues with the headlight wiring, bulb life and the headlight switch. I would want to check all these items prior to replacing the bulbs.

Q. I have a 1999 Mercedes with 150,000 miles. The car has never given me a problem, until recently. When I start out in the morning and shift from 1st to 2nd, I hear a clunk. What do you think it is? And how should I proceed?

A. The car needs to be road tested by a technician, then put on a lift to find the source of the noise. The problem could be worn universal joints in the drive shaft, worn center support bearing and/or loose or worn engine and transmission mounts. One overlooked area that I have also seen in some Mercedes models is the insulation above the drive shaft, which can rub and make a similar noise.