Q. Dear Tom and Ray:

What should I do? Everyone except my wife keeps telling me to replace "my" truck! It's a 1985 Ford F-250 XLT Lariat with a towing package, captain's chairs and an extended cab. Some rust is showing in the expected spots, and looking under the front of the truck makes co-workers want to call the Environmental Protection Agency. I have hauled 3,800 pounds of sand with this truck without any problem. Camping is no problem, either, and is 9 miles per gallon so bad? Is everyone else right or is this still America, where a man's truck is special?

-- Ed

A. RAY: You do whatever the heck you want, Ed. This is still America, where the Constitution guarantees every citizen the right to life, liberty and the right to drive a big, ugly truck if he wants.

TOM: There are two basic factors when it comes to car and truck replacement. One is economic. When the cost of making your vehicle safe and reliable gets to be more than a replacement car would cost, then you have an economic reason for upgrading. Nothing in your letter suggests that's the case. The "EPA" comment suggests you have some external engine leaks, which can almost always be fixed.

RAY: The other factor is emotional. When you fall out of love with your car and stop caring about it, then you have an emotional reason for getting another set of wheels. Obviously, that's not the case here, either. You love this truck. And while we won't comment on the psychological abnormalities that go into loving a pickup truck, clearly there is no reason for you to trade this baby in.

TOM: People may criticize your 9 mpg as environmentally wasteful. But it's also environmentally wasteful to build a whole new pickup truck.

RAY: Right. Just think about the number of naugas alone that have to sacrifice their lives for the Naugahyde seats!

Dear Tom and Ray:

I have a '97 Nissan Sentra. I changed the spark plugs at 30,000 miles and just did it again at 60,000. The owner's manual says the spark-plug gap should be between .039 and .043 inches. I set them at .040 and the car runs fine. I checked the gaps on the old plugs I pulled out and they were between .050 and .060--way off! But the car had been running fine. How important is the gap?

-- Daniel

RAY: Well, as you've discovered, Daniel, not that important. Most cars will run fine even with the gap pretty far off.

TOM: And in your case, what probably happened was that the plugs burned down to .050 or .060 from their original settings. That's what happens to old plugs--the metal in the electrode and the tip wears down from all that firing. And that's one of the reasons you replace old plugs.

RAY: At some point--it may be at .070 or .080, in your car--the engine would have developed a miss because the gap would have gotten so big that the spark couldn't jump it. And if you had other problems--like a weak coil or bad spark-plug wires--that miss would have developed sooner rather than later.

TOM: The gap recommended by the owner's manual is the optimal gap. That's where the engine runs most efficiently. But in modern cars with otherwise healthy, high-energy ignition systems, within 10 or even 20 thousandths of an inch either way, most spark plugs will usually fire well enough so that you won't notice any difference in performance.

Got a question about cars? Write to Click and Clack in care of this newspaper.

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