Car Talk: Long, leisurely drives great for retired cars and people

Pat: Starting and running the car for a very short time is among the worst things you can do, Pat. It’s not as bad as my brother leaving his ‘74 Chevy convertible top down all winter and letting a family of raccoons live in the backseat, but it’s not a good idea.

When you start the car and only let it run for a few minutes, you send water vapor (a byproduct of combustion) into the cold exhaust system. Until the exhaust system fully heats up, that vapor will condense inside the exhaust pipes and turn into water.

And then, when you shut off the car, that water gets to work rusting your exhaust system. Or certainly makes it rust faster than if you had just left the car sitting in the driveway. And if you do that every day, Pat, you’re going to be Meineke Customer of the Year.

Water vapor from the combustion process can also get into the oil. And again, once the engine fully heats up, the water gets vaporized and expelled. But if you just run the car for a few minutes, you can make yourself more susceptible to internal engine corrosion.

Driving once a week for a few miles is better but could result in the same problem, depending on how long you allow the engine to run. And a few miles may not be enough to fully charge the battery.

So, my advice would be to drive it once a week for 5 or 10 miles. That’ll be enough to charge the battery, allow the engine and exhaust system to get to full operating temperature, and just generally keep things lubricated and moving. If you did that every two weeks, you’d be fine, too. And if you were willing to disconnect the battery, you could go much longer without doing any harm to the car.

So, the solution is to find a place you look forward to going to once a week, Pat. Somewhere that requires you to drive 5 miles or so from your home. I’d suggest either a good ice cream shop or a girlfriend. Enjoy your retirement.

Got a question about cars? Write to Ray in care of King Features, 628 Virginia Drive, Orlando, FL 32803, or email by visiting the Car Talk website at www.cartalk.com.