QDear Tom and Ray: Guys -- I love your show and your column, and have followed them from NY to NJ to IL to NJ to NY to NC to NJ again. My wife's superb purchase of a 1996 Toyota Camry, which has been a workhorse for almost 10 years and 110,000 miles, apparently now has a head-gasket leak. I have never had to add oil between oil changes. So, I guess I can spend $2,500 now to fix it, or take my chances and maybe need a new engine one day. How long can I get away with just watching the oil-pressure gauge and dipstick? -- Steven

ARAY:It depends on what kind of leak the head gasket is causing, Steven. A cracked head gasket can create several kinds of leaks.

TOM: It can allow oil to leak from the oil passages to the outside of the engine. You'd see oil seeping out where the cylinder head meets the block.

RAY: If it's leaking oil at such a slow rate that you never have to add any between oil changes, it may leak for years like that and be just fine.

TOM: However, if it's letting oil mix with your coolant inside the engine, then you've got to fix it. The problem isn't so much the oil that gets into the coolant, as the coolant that gets into the oil. Coolant is a lousy lubricant, compared with motor oil. Trying to lubricate an engine with a mixture that's half antifreeze means you will need a new engine soon.

RAY: The same can be said if a broken head gasket is allowing coolant to get into the cylinders. That means you're burning up your coolant and it's coming out your tailpipe. At some point, the leak will get a lot worse, and you will run out of coolant and turn the engine into a solid, single-piece, 600-pound paperweight.

TOM: So unless it's only leaking oil externally, and slowly, I'd recommend that you go ahead and fix it. If properly cared for, this engine could easily go another 110,000 miles. Failing to fix it could result in having to buy your wife a brand-new Camry -- which, as you know, Steven, is a heck of a lot more than $2,500.

Dear Tom and Ray:

My daughter's boyfriend bought a used car. After driving it for a month and a half, the battery needed to be jumped. A friend of mine helped the owner jump the battery from another vehicle; the car wouldn't start. So, they removed the battery and set it on the ground. A while later, one of the guys bent over the battery and merely put his hands on the sides, and it blew up in his face, causing the loss of his sight in one eye. Why did this battery blow up? It was not dropped. -- Ana

TOM: It has nothing to do with the battery being on the ground. The reason batteries explode is that dead or dying batteries can emit hydrogen gas. And we all know -- see "Hindenburg" -- that mixing hydrogen gas with a spark is a bad idea.

RAY: So, the question, in your case, is where did the spark come from? Was anyone around the car smoking? A floating ember could easily have provided the spark.

TOM: Or was someone wearing polyester pants? If your friend had built up a static charge and touched the battery, a spark could have jumped from him to the battery.

RAY: So we don't know what provided the spark. But something ignited the outgassing hydrogen, and that's what caused the explosion.

TOM: Your letter also is a good reminder that safety glasses really can save your eyesight. So wear 'em.

Got a question about cars? Write to Click & Clack in care of The Post, or e-mail them by visiting the Car Talk Web site at www.cartalk.com.

(c)2005 by Tom and Ray Magliozzi

and Doug Berman