A leaking gas tank wastes expensive gasoline, and it's dangerous. If your car is parked with a puddle of gas under it and somebody happens to toss a match or cigarette there, well, goodbye family chariot.

Fotunately, it's easy to fix a leaking gas tank -- as long as the hole isn't bigger than a dime. A patching material made by Loctite Corporation -- called Instant Gas Tank Repair Patch, part number 12020 -- can do the trick. If your parts shop doesn't have it in stock, it can order it for you; chances are good, though, that it will be in stock.

Once you get it, here's what to do:

First, clean the area around the leak with a cloth or paper towel; the patch won't stick to a dirty surface. If necessary for stubborn grease patches, squirt on a little carburetor cleaner and wipe off -- it's excellent for getting grease and dirt off metal parts and commonly available.

Be sure your hands are clean; if you have dirt, oil or grease on them, you can contaminate the patching material.

Don't worry if the-cleaned area around the hole is wet with gasoline -- gasoline doesn't affect its ability to adhere.

Next, open the blister pack containing the patching material. Tear off enough patching material to do the job. You need nothing to fill the hole and to cover an area 1/2" wide around the hole.

The patching material has two different colors: half dark brown, the rest much lighter. Knead the two parts together until it's all one color.

Then form the patching material into the shape of a pencil (the package has a diagram and instructions) and push the pointed end into the hole.

Put the paper liner the patching comes in against the patching material and push until you have flattened the material outside the tank evenly around the hole. The material tends to stick to your fingers, so you have to use the liner paper to keep it from pulling away from the tank.

For best results, the manufacturer recommends that the patching material be at room temperature; try to wait until it's over 40 degree F. for your repaiur -- that'll make it more comfortable for you to work, too.

Check to see if the leak has stopped. If not, the tank must be repaired at a shop that specializes in gas-tank repairs, where they'll remove the tank, clean it to remove explosive gasoline fumes, and weld the hole or crack. CAUTION: It should go without saying, but anyway: Never smoke around a leaking gas tank.