Q. I am currently in the market for a new car. I was originally leaning toward a 2010 Honda Accord V6 Coupe, if I could buy it for $25,000. After doing some research, however, it seems dealers will only go down to about $28,000. Since then, I’ve come across a certified pre-owned vehicle—a 2007 BMW 335i with 37,000 miles—being sold for about the same price as the Honda. Is a certified pre-owned BMW an equal or better option over the Honda Accord?

A. Because the BMW is a certified pre-owned vehicle, in my mind, this makes all the difference. Certified pre-owned BMWs are typically the cream of the crop. They have been completely checked out by certified BMW technicians and have additional warranty coverage for up to six years, or 100,000 miles—whichever comes first. The Honda Accord is a great car; the last coupe that I drove returned good mileage, handled well and had plenty of power. As good as the Honda may be, if you are a driving enthusiast, the BMW 335 is a great car to drive. Of course, because the Honda has front-wheel drive (and the BMW has rear-wheel drive), it will be better in wintery conditions. The BMW looks like a good value and, over time, will actually depreciate less than the new Accord. Then again, there is something comforting about buying a new car, especially one that is made by arguably the best manufacturer in world. When it comes right down to it, I recommend buying the car you will enjoy driving.

Q. While spending the winter in Florida, I went into a few well-known tire shops that seemed to be pushing brake fluid replacement with their brake jobs. I have been driving for 60 years and have never run into this before. My second question concerns my 2002 Town Car; can I change to synthetic oil after driving 50,000 miles on regular oil?

A. Years ago, brake fluid replacement occurred in conjunction with hydraulic component replacement. Brake fluid is hygroscopic, meaning it seeks moisture. This moisture can cause rust, which is very detrimental to the anti-lock brake systems in today’s vehicles. Replacing the brake fluid when performing a brake repair could limit problems in the future; in fact, some vehicles have specific recommendations for replacing brake fluid. Regarding switching to synthetic oil, this is not a problem. In the past, people would warn against this, saying the oil would cause the engine to leak. This is not true, although synthetic oil will find a leak, if one does exist.

Q. I have a 2005 Nissan Frontier and the transmission fluid is foamy and burned. Should I change the fluid? If so, what kind should I use?

A. Transmission fluid tends to foam if the transmission is overfilled. At this point, I would change the fluid using only Nissan J-Matic fluid. Nissan warns against using any fluid other than genuine Nissan automatic transmission fluid.

Q. We own a 1992 Saturn 4-door sedan that seems to shudder and slip when I accelerate. It acts like the gas is shutting off, but it only does this under hard acceleration. What do you think it could be?

A. There are many problems that match your description. It could be the transmission slipping, an ignition misfire, faulty sensor or something else. I recommend bringing the car to a qualified technician for a road test and diagnosis.

Q. I own a 2001 Dodge Ram 1500 truck. The check engine light turns on and off; currently, it is back on again. A test showed the code PO138, which indicates a problem with the oxygen sensor. I was told a new sensor might not correct the problem, however, and that it could be a computer issue. What do you think?

A. Computer fault codes can sometimes be misleading, even to the best technician. For correct diagnosis and repair, a specific trouble shooting procedure should be followed. Also, the wiring, connections and sensor need to be checked before the computer is considered. I have seen many cases where the heater circuit in the oxygen sensor fails, and in these cases, replacing the sensor solves the problem.