QDear Tom and Ray:

I am a student in Boston with a car that is originally from Texas. I have a 1996 Chevrolet G Van that has more than 150,000 miles on it. The car had been working really well until last fall. This was its first real winter. Basically, I have to jump-start my car every time I want to turn it on. I am hoping that you might have an idea of what I can do to fix it. -- Hannah

A RAY: Two things come to mind, Hannah. The first is simple. I think you may have a dead cell in your car's battery. If one cell is dead, the battery may be producing only 10 volts instead of 12. That's enough to work the lights, the radio and the stereo system. But the starter motor needs a full 12 volts, or it just won't move.

TOM: The solution to that is a new battery. That'll cost you 75 bucks. Just flag down one of the guys in your parking lot and say: "Excuse me, would you mind putting in this new battery for me?"

RAY: Or just go to a gas station, and have them do it, Hannah. Because they can check for the other possibility: a current drain. It could be something like a light in the glove box that's staying on all night. It's very easy for your neighborhood mechanic to test your battery and your charging system, and to check for a current drain. That shouldn't cost very much. But I'd bet on the battery.

Dear Tom and Ray:

Recently, while test-driving a Jeep Liberty, my wife asked the salesman about the difference between "full-time" and "part-time" four-wheel drive. I ran with the question, explaining that the part-time should be used only during certain slippery conditions and disengaged when the condition ends. "Full-time" can be left on indefinitely at the pleasure of the driver. "No, no, no," replied the salesman. "You've got it all backward. If you want to leave it on all the time, put it in 'part-time,' because of something to do with the transfer case. The 'full-time' should only be used on a full-time basis when it's slippery outside." Am I stupid? -- Jerry

TOM: Only if you believed the salesman.

RAY: Your explanation is exactly right. For the vast majority of drivers, full-time four-wheel drive, or all-wheel drive, is far superior to part-time four-wheel drive. Not only do you never have to worry about when it's safe to use, but since it's always on, it's ready when you hit an unexpected slippery patch of snow, sand or extra-virgin olive oil.

Got a question about cars? Write to Click & Clack in care of The Post, or e-mail them by visiting the Car Talk Web site at www.cartalk.com.

(c)2005 by Tom and Ray Magliozzi

and Doug Berman