Q. Dear Tom and Ray:

When is it time to stop following the manufacturer's maintenance schedule? I have a 1993 Volvo 940 Turbo Wagon with 102,000 miles on it. For the most part, I have brought it to the dealer for all of the scheduled maintenance. That means spending something like $500 or $1,000 a year, even if the car is running perfectly when I bring it in. (To be fair, those bills included brake jobs and exorbitant repairs to such essential equipment as the seat heaters.) But at this point in the car's life, should I continue to go for the hefty cost of the routine maintenance visits or just wait until things break?

-- Steve

A. RAY: Keep doing the maintenance, Steve. This is a mistake a lot of people make. Once they get to 75,000 or 100,000 miles, they assume the car is on its way downhill anyway, so they throw away the book and stop doing the routine servicing. And it's a self-fulfilling prophecy.

TOM: Right. You stop taking care of it, things start to wear out, and you take the car in one day and they tell you you need $8,000 worth of work. And you say, "That's ridiculous. On a car with 120,000 miles, I'll just junk it."

RAY: But if you kept doing the maintenance, you'd invest your $500 or $1,000 each year, and you'd probably never face the $8,000 dilemma.

TOM: Right. They'd get it $1,000 at a time over, say, eight years. And our Volvo-owning customers tell us it doesn't hurt nearly as much that way.

RAY: Actually, if you keep up on the maintenance, you'll likely spend less in the end and have a car that runs better and lasts longer. So the answer to your question--"When is it time to stop following the manufacturer's maintenance schedule?"--is "never."

Dear Tom and Ray:

Can you think of any reason why a catalytic converter would catch fire while you're driving?

-- Sharon

TOM: No.

RAY: I've certainly never seen it happen. And I've had cars come into the shop with converters that were glowing red.

TOM: But it's possible for things around the converter to catch fire. If your engine was running rich or your timing was very retarded, a lot of the gasoline could have been combusting inside the converter instead of the cylinders. (Those are the most common explanations for red-hot converters.)

RAY: So if your converter was running hot and you ran over a garbage bag and it got stuck underneath your car, the garbage bag could have caught fire. The same could be true of a bunch of dried leaves or a flowering tulip tree that you ran over 20 miles earlier and wedged between the converter and the floorboards.

TOM: But I've never seen a converter itself burst into flames. If you're looking for an explanation for a fire that started under the car, look for something the converter could have ignited rather than the converter itself.

RAY: And if the car still exists (you don't indicate in your letter), make sure the fuel-air mixture and timing are correct and that the converter is operating properly before you drive over your next tulip tree, Sharon.

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(C) 1999 by Tom and Ray Magliozzi and Doug Berman