Q. I own 2003 Buick Century with 37,460 on it. Since I have owned it, service has only been performed at the Buick dealership. Recently I was told a gasket is leaking and causing the coolant light to come on. The service manager told me the repair will be just over $1,100.00. My question to you, has there been any kind of bulletin or recall issued? The garage tells me this is a very common problem.

A. The six-cylinder engine that is used in your Buick and many General Motors vehicles has been subject to a failure of the intake manifold gasket. Although there have been technical service bulletins issued there have been no recalls.

4Runner brake issue

Q. My Toyota 4Runner is 12 years old with 190,000 miles. With wintertime temperatures, I can step on the brake to put it in gear and the brakes will come back to the top and then cannot be depressed. Depending on the severity of the cold, I have to wait 20 to 30 seconds or more before I can step on and press the brakes down again. My mechanic has replaced my brake booster (albeit a used one) to no avail. Any ideas?

A. Have your repair shop check for condensation in the brake booster vacuum line and check valve. As moisture builds up it will block the vacuum to the booster and cause this condition. Replacing the vacuum booster check valve may solve the problem.

Pathfinder timing belt

Q. I have a 2000 Nissan Pathfinder with 73,000 miles on it. When should I have the timing belt replaced and approximately what do you think it should cost? Should I also replace the water pump?

A. The timing belt on your Nissan should be replaced at 105,000 miles so you still have time. When that time comes, the timing belt is about $45.00 and takes about four hours of labor to replace it. The water pump is not an integral part of the timing belt system so it is not necessary to replace the two items together unless the water pump shows signs of wear.

Cross-over SUVs

Q. I am considering a cross-over SUV type of vehicle. I really like the Nissan Murano and Rogue, but other than their style and the online reviews I read, I don’t know much about them. What do you think about these vehicles and is there something else you would recommend?

A. The style of the Murano and Rogue set them apart from the competition. Both offer a decent ride and secure handling. I would also look at the Honda CRV, Hyundai Sante Fe and the Mazda CX7. The CRV offers a great reputation and resale value, the Sante Fe has a great warranty and the CX7 has styling to match the Murano.

Polish before wax

Q. I just bought my first new car and want to treat it right. To keep it looking new, should I wax the car first and then use a polish, or polish then wax?

A. You polish then wax. The polish is designed to remove imperfections and the wax to protect and nourish the paint. A great Web site for vehicle appearance care is Meguiar’s Wax, www.meguiars.com.

‘OD’ for better mpg

Q. I recently bought a used Toyota Camry. In my car there’s a button I don’t understand. It’s marked “OD ON/OFF.” What does this mean and when do you use it?

A. The button is for the overdrive portion of the transmission. When the transmission is in overdrive (overdrive on), the engine runs at a slower speed and will deliver better fuel economy. This is the selection you should use most of the time. If you are towing a small trailer or driving hilly areas you could select overdrive off, to minimize shifting.

Better gas?

Q. My 2006 Audi A3 was in for scheduled maintenance and the mechanic told me to use Shell gas instead of others such as Mobil and Hess. I always use premium because of the turbo engine along with synthetic oil. He said his reasoning was because Shell is the only company that still adds detergent to its gas mixture. Do I really need to buy only Shell gas or could I buy a fuel injection cleaner at Autozone or some other parts store?

A. All gasoline by regulation is required to have a minimum amount of additives to help keep the fuel system clean. Shell gasoline and some others are considered “Top Tier” fuel and have additional chemicals added to their mixtures. Is it necessary to use only Top-Tier gasoline in your Audi? In my opinion, no. Although as in the past when I have answered this type of question I’m sure I’ll hear from readers who disagree.

projocars@projo.com