Twice per month, Lauren Fix, The Car Coach®, will answer your questions here at AOL Autos about your cars, trucks, driving, tires--anything to do with your car or truck.

Dear Car Coach:

My 2008 Jeep Liberty has been a great vehicle, except for the money I have spent on brake repairs to fix an annoying "pulsation." I feel it when I step on the pedal, and it is making me think about trading it in for something newer. I have had three different service places fix my brakes, and each one gives me a different story for why the pulsation happens. Any insight?

MP, East Aurora

Dear MP,

More and more customers are frustrated by repeat brake problems on newer cars. Although the noise is not as big an issue as it was just a few years ago, an even more annoying, unnerving, and unsafe braking condition occurs. The problem is often called "pulsation" and is a condition that causes the brake pedal to "push back" against the driver's foot whenever the brakes are applied. Often times when the brakes are checked the technician's verdict is that the brake discs, or (as they are commonly referred to) rotors, have warped. Replacing these "warped" rotors resolves the problem......for a while. After a few miles (usually 7000 to 10,000 miles) the condition can return.

Most times the discs (or rotors) are not warped. Rather, they actually develop two thin spots 180 degrees apart from each other on the precision-machined surface that the brake pads "clamp" on to when the brakes are applied. This happens when the increasingly tight clearances that are required in today's braking systems (often less than the thickness of a human hair) are no longer maintained. These tight clearances are required so that safety initiatives like anti–lock Brakes and vehicle-stability-control can function effectively. There can be many causes for this lack of clearance, but few require parts to be changed or replaced.

Actually a brake disc on today's brake system needs to be "matched" to the vehicle whenever it is serviced or removed just like a tire needs to be balanced with a wheel whenever it is removed or vibrations are evident.

Many shops have special equipment to check for proper "Rotor Matching," and offer various methods to repair mismatching. When this is completed your brake repairs will last longer, your vehicle will stop better, the annoying pulsation is gone, and your vehicle's safety systems that rely on your brakes will function as designed. Ask your repair shop if they measure "lateral run-out" every time the brakes are serviced and that they ensure that it is below the manufacturer's specification for your particular vehicle. Also, make sure they have the needed equipment to repair excessive "Lateral Run-Out" if it is discovered during the measuring process.

Keep your Jeep. Have your "Rotors Matched" before the pulsation returns! To find a shop near you that is trained and equipped to perform proper rotor matching, you can visit the following web site www.procutinternational.com/zipfind.aspx.

Dear Car Coach:

My locks freeze during winter because my car sits outside. What can I do if I go out in the morning, and the locks are frozen? I'm afraid of breaking the key off in the lock. And if I use my remote key fob, the door sticks shut. Any tips?

MN, Hamburg

Dear MN,

No matter where you live, when the temperatures begin to drop, there's a chance that you will find a frozen car-door lock. Plan your attack on frozen locks in advance before you get stuck out in the cold.

The first thing you should do when encountering a frozen door is try accessing the car through other doors, or the rear hatch if necessary. Jump in, start the engine, and let it run for several minutes. It won't take long for your car to heat up and thus warm the locks on all the doors.
Here are some other quick thawing solutions:

Things You'll Need:

-Matches or lighter
-Hair dryer
-Toilet paper tube or straw
-Lock de-icer
-WD-40

1. Heat your key. Sometimes a frozen lock needs a little warmth to get the tumblers moving. Wearing thick gloves, carefully use a match or lighter to heat your key and then insert it into the lock. The heat will melt ice inside the lock and allow you to unlock the door. WARNING: Modern key fobs contain computer chips that are easily damaged. Unless you have a single key, this is NOT a good option.

2. Keep a straw or toilet paper tube handy during winter months. In the event that your lock freezes, place the tube over the lock and warm it with your breath. This technique may look silly, but it works. Your breath can be all that it takes.

3. Using a hair dryer to heat the key or the lock itself is another good option, but finding an electrical outlet nearby can be a problem. You'll need a long extension cord or a portable hair dryer if your car isn't within reasonable range of an outlet.

4. Prevent your locks from freezing by keeping a can of de-icer or WD-40 on hand and spraying your locks at the end of the day. Since most frozen door locks are the result of condensation inside the tumblers, de-icer will help keep the condensation from freezing. You can find de-icer in most hardware and automotive stores or in gas stations and convenience stores during the winter months.

Warning: NEVER pour hot water over your lock. This will increase the amount of water inside the lock and result in future frozen locks.

If you think that using a remote is the best solution, think again; doors freeze shut too.
One final tip: cover a rag with baking spray and wipe the weather strip (rubber door seal) in the evenings to prevent your door from sticking in the morning.

Dear Car Coach:

Do you think All Wheel Drive (AWD) cars are the best choice for winter? Should I get aftermarket wheels on which to mount snows? I tried them for a BMW, but they vibrated at highway speed. Also what brands of snow tires do you like? Your thoughts?

BD, Orchard Park

Dear DB,

We live in Buffalo, NY, so I am very familiar with winter driving. I prefer all-wheel-drive vehicles in winter, but we actually use snow tires on our vehicles and get separate rims. I have purchased by snow tires at www.tirerack.com. The best way to use Tire Rack is to order your tires and have them shipped directly to the shop where you will have them balanced and installed. To avoid vibrations you must have the wheels spin balanced. The best winter tires I've tested are Michelin and Bridgestone.