Dear Doctor:

I have a 2000 Subaru Legacy with 63,000 miles that recently needed head gasket replacement and then coil replacements, which was performed at a repair shop. Now I suspect that the suspension needs work. I wonder if there are certain repairs that a car owner might be better off having performed by the dealership technicians, assuming that they’ve been exposed to the car’s problems and training on how to fix these problems.

— Mary

Dear Mary: It’s not unusual to have failing head gaskets on older Subaru vehicles along with oil leaks. Ignition coils, knock sensors and catalytic converters are also very common issues. Suspension components, such as sway bar links and sway bar bushings, wear and cause noises over bumps. As for your choice to take the vehicle to a repair center vs. a dealership, I recommend you get a price estimate — and ask the dealer whether they would even want to work on a car that is this old. As long as the shop has ASE-certified technicians, then I think you’re in good hands.

Dear Doctor: I have a 1994 Ford Probe that I use only occasionally. When not driven for a week the battery goes dead. My mechanic is unable to find the problem. What tests should be performed in order to trace this problem?

— Evelyn

Dear Evelyn: The battery should stay alive for six to eight weeks without going dead, as long as it’s a good battery. The first step is to check the battery condition. Then check for parasitic drain. This is done with a digital amp meter connected to the battery and the battery cable. The technician will check for how much drain is in the system — 50 mili amps is the maximum draw on this vehicle, but less would be better. I have seen things from a small glove box light, hood or trunk light cause this problem. Everything that has retained accessory power with the ignition key off is suspect.

Dear Doctor: My Acura RDX with the turbocharged four-cylinder engine has an occasional whining noise. The technician could not determine the origin. He told me it could be the anti-lock brake system priming itself. Any thoughts?

— Lyndon

Dear Lyndon: Whining sounds are usually from belt-driven accessories, such as the power steering pump, alternator, even the air conditioning compressor. You can do some homework by writing down what you are doing when this noise occurs, such as your speed, whether your foot is on the gas pedal or when driving up hill or coasting down a hill. Is the engine cold or at normal operating temperature? All this information will be a big help to the technician.

Dear Doctor: My Ford Ranger has 180,000 miles and is in great shape, but gas mileage is only 8-13 mpg. I changed the oxygen sensors and the mileage seems to be improving to about 17 mpg. I’m thinking of putting an aftermarket exhaust system and intake system on the truck for improved sound and a “coolness” factor. What can I do?

— Bob

Dear Bob: Oxygen sensors get lazy and usually cause the engine to burn more fuel than it needs to. And sometimes lazy oxygen sensors don’t set the check engine light. Low restriction exhaust, cold intake performance air filters should increase mileage. Full synthetic engine oil and rear differential fluid, proper tire pressure and tire tread design will also make a fuel mileage improvement.

Dear Doctor: My wife’s 2017 Subaru Legacy does not have a parking brake lever or pedal. Instead it has an on/off switch on the console, which looks like it’s designed for use when car is already stopped. What now serves as the emergency brake?

— Edward

Dear Edward: Great question. Most of today’s newer vehicles are equipped with an electric parking brake. This is a parking brake — not an emergency brake. In the old days we had a mechanical parking brake, though many owners did call it an “emergency brake.”