Dear Tom and Ray:
What's the minimum a car should be driven to keep the battery charged and the fluids doing what they are supposed to do? My daughter has taken a job 1,500 miles away and left behind her 2000 Nissan Maxima with more than 267,000 miles on it. It's in pretty good shape, other than a small but persistent valve-cover oil leak and a power-steering-fluid leak and maybe a mystery leak contributing a few drops a day. I drive it to work one day a week, 12 miles each way, and maybe a mile or two at lunchtime. Is 25-26 miles, one day a week, enough to keep the car in shape if my daughter ever wants it again? Thanks! — Dave
Ray: That's perfect, Dave. Actually, you probably can get away with half of that.
Tom: What you don't want to do is just start the car, run it for a few minutes and shut it off. You'd be better off not starting it at all rather than doing that.
Ray: Once you use some battery power to start the car, you want to give the alternator a chance to charge the battery back up.
Tom: And, more importantly, you want to give the exhaust system time to heat up and evaporate the moisture that condenses out of the exhaust when the exhaust system is cold. Water vapor is a natural byproduct of the internal combustion process, and if it's allowed to condense and remain in the exhaust pipes, the exhaust system will rust prematurely.
Ray: The easiest and best way to maintain the battery and the exhaust system is simply to drive the car a little bit. So what you're doing — an occasional short drive — is perfect.
Tom: The one additional suggestion we'd make is to change the oil every six months or so. Even though you won't be anywhere near the oil-change interval in terms of mileage, it's not a bad idea.
Ray: So keep doing all that until something serious goes wrong with the car, Dave. And then call your daughter and tell her you suddenly don't have room in the garage anymore, and she needs to come pick it up.
(Car Talk is a nationally syndicated column by automotive experts (and brothers) Tom and Ray Magliozzi. Write to them at the Car Talk website.)