I own a '93 Dodge Caravan with 65,000 miles. When the van had 50,000 miles, I started noticing oil spots on the driveway and garage floor. Four hundred dollars and a new head gasket later, the oil leak was supposed to be corrected. It wasn't.

After several more trips to the dealer, they decided that the valve cover gasket needed replacing, and they did it free of charge. Funny as it seems, I still have an oil leak. After taking a 1,000-mile trip and adding a quart and a half, the dealership says the rear crank seal is bad and needs to be replaced. That would be another $300.What do you think? Should I unload this thing as soon as possible? Or is it just coincidence that I've had three gaskets go bad within a year? I'm told not many people bother to replace the rear crank seal, but I hate having oil spots on the driveway. - Tom

RAY: Three bad seals, huh? The Monterey Bay Aquarium had three bad seals one year. Apparently, they put a few posters for the shark exhibit near the seal tank, and they never heard another peep from them.

TOM: I think it is a coincidence, Tom. Head gaskets shouldn't blow at 50,000 miles, but they sometimes do. It could have been due to poor manufacturing, or it could have been caused by engine over-heating.

RAY: And the valve cover gasket was probably leaking because they put it back on wrong when they did the head gasket job. That's why they replaced it for free when they later discovered it was leaking.

TOM: The rear crank seal (more commonly called the "rear main seal") leak is probably unrelated to the other two. However, it's worth checking the Positive Crankcase Ventilation (PCV) system before you go any further. The PCV system is supposed to let pressure and fumes out of the crankcase. If too much pressure builds up in there, it could cause seals to blow.

RAY: If your PCV system is operating correctly, then the leak is more of an aesthetic and environmental matter at this point. A quart and a half of oil every 1,000 miles is not much, mechanically speaking. Certainly not enough to endanger the engine, provided you keep an eye on the oil level and never let it run too low.

TOM: And for the $300 it costs to replace the rear main seal (that's $3 for the seal, and $297 for labor, by the way), you could buy 300 quarts of oil. That's enough, theoretically, to cover you for another 200,000 miles, which you'll only get out of this car in your dreams!

RAY: So it's up to you, Tom. Fix it if it bothers you or if you're particularly concerned about the environment, or just keep an eye on your oil level and park over some pizza boxes from now on.

The Magliozzi brothers' radio show "Car Talk" can be heard each Saturday at 10 a.m. on KUER FM 90.1 If you have a question about cars, write to Click and Clack Talk Cars c/o King Features Syndicate, 235 E. 45th St., New York, NY 10017. You can e-mail them by visiting their Web site at (http://cartalk.msn.com).