Mixed signals on lubing lug nuts

Dear Mike: I’ve read your column with interest over the years, and I agree with you wholeheartedly about the issue of lubricating lug nuts lightly with oil before tightening them. But my owner’s manual specifically tells me never to oil the nuts, that they must be installed dry.

Who’s right?

— J.S., La Grange, Wis.

A: If there’s anything that makes my teeth grind, it’s watching a mechanic with an air wrench tightening lugs until they squeak and blow powder. This practice not only makes it difficult for the driver to remove them later — probably at the roadside in the rain and mud — but it overstresses the fasteners and could make them snap off, which has potentially disastrous consequences. It’s also likely to warp the brake discs, leading to pedal pulsation, reduced brake life and increased stopping distances.

It’s been brought to my attention that some car manufacturers coat new lug threads with some sort of dry lubricant to permit proper assembly at the factory. So if your owner’s manual says not to lubricate the lugs, then don’t lubricate the lugs.

One compelling reason for not lubricating lugs is illustrated here: I had someone bring me a Porsche with a wobbly front end. It was very unstable at speed. As the Porsche had aluminum-alloy lug nuts, the owner had installed the closed-end nuts with a generous dab of wheel bearing grease. The captive grease inside the nuts had prevented them from bottoming on the wheels, allowing them to wobble. Scary, times four.

Here’s how to attach your wheels:

•Clean the mating face of the wheel and hub of any debris or rust. Wire-brush if you must. The wheel must sit absolutely flat. Then lubricate. I like to use a thin film of oil or anti-seize compound — this will make the wheel easier to remove in the future by preventing corrosion. Hang the wheel on the studs or bolts.

•If your car manufacturer does not prohibit lubing the lugs, put a drop or two of oil or a match-head-size dollop of grease on the threads and chamfers. Don’t use anti-seize compound here because its lower coefficient of friction will make the lugs too tight even if you torque them properly.

•Finger-tighten. Look up the proper torque value for your lugs. In a star-shaped pattern, tighten the lugs to half the specified value with a torque wrench. Now, again in a star pattern, tighten the lugs to their final value.

Dear Mike: Whatever happened to the chains you used to see dragging along on the ground underneath big trucks to dissipate static electricity? What could I use to prevent the spark of electricity I get in cooler weather when I slide out of the car?

— D.T, Gardnerville, Nev.

A: If trucks are no longer dragging those chains, it’s certainly not because there is no more static electricity. In this day of self-serve refueling, there have been many cases of static-caused gasoline fires. There’s no need for any of them.

Here’s the typical scenario: You get out of the car, swipe your credit card and begin fueling. Then you return to the car to put away your credit card, brushing your polyester-clad backside over the fabric seat, building up a substantial electric charge. When you touch the pump handle again, the spark ignites fuel vapors in the area. You see the fire and, in a misguided attempt to put it out, yank the pump nozzle free, turning it into a short-range flame-thrower that sprays gas all over your car, the ground and you. Bad.

The data from these fires seem to favor women for two reasons. They keep their credit card or money in their purse on the car seat, rather than in their wallet in their hip pocket — necessitating a trip back inside the car. And, men are more likely to wear natural fibers like cotton, which are less likely to create sparks.

Here’s how to refuel your car safely: Extinguish all smoking materials. Put your cellphone down. Shut off the engine. Remove all small children and elderly people who can’t run like the dickens from the car. Touch the metal gas pump frame with your bare hand to dissipate any static. Leave your hand in contact with the metal pump nozzle while you’re pumping gas, no matter how cold the weather.

If you must get back in the car, touch the metal pump frame with your bare hand to dissipate any static before you reach for the nozzle. When the pump clicks off, hang the nozzle back up. Most importantly, if a fire does start, do not remove the nozzle from the tank. Do run for the attendant to have the pump shut off at the emergency switch, and then you can use a fire extinguisher to put out the small fire.

When filling portable gas cans, always remove them from the vehicle and set them on the ground. If they sit in the bed of a pickup with a liner, or on the carpet in the back of an SUV, they can build up a static charge that can ignite the fuel vapors. Touch the pump before filling, keep the nozzle in contact with the can, and fill slowly.