Dear Tom and Ray:

My 1992 Honda Civic LX sedan has 155,000 miles on it and has spent many Minnesota winters outside in the salt and the cold. The car runs great, but it is very rusty. There is a hole in the trunk. A few of the rear-bumper cover clips rusted through, leaving the bumper hanging (I repaired it with self-tapping screws after a long search for enough steel to hold them). The fenders are rusted through. There is rust on the frame -- even rust around the shocks. I always planned to drive the car until its wheels fell off. However, I'd rather not literally have the wheels fall off while I'm driving. And I would like a little nonoxidized steel around me in the event of a crash. I don't care about the car's appearance, but I am concerned about safety. How can you tell when a car needs to be retired based on rust alone? -- Marty

TOM: Sounds like you're just about there, Marty. In fact, you might have overshot a little bit.

RAY: The point at which the car becomes unsafe -- rather than just ugly -- is when the rust starts affecting the structural underpinnings of the vehicle.

TOM: For instance, unibody cars like your Civic have a floor pan, which is a big, reinforced piece of sheet metal that serves as the car's frame. Every important piece of the car ultimately is attached to that floor pan. So if the floor pan starts rusting away, you have to assume that, in an accident, the car will turn to dust.

RAY: Which, admittedly, will save you some money on post-accident towing fees. You'd just pick up the plates and walk away.

TOM: But you won't have to care about that, Marty, because it'll be your heirs who will be dealing with all that stuff.

RAY: So, what you need to do is go to your regular mechanic, if you have one, and ask him to check out the floor pan, the engine cradle, the shock towers ... basically all of the structural components of the car. And if he says they're rusty, or he reminds you that he TOLD you they were rusty a year ago when he last saw you, it's time to junk the car, Marty.