John's comments re lubricating (or not) nuts and studs before torquing 
raised a question or two so off to the web.
On Wednesday, August 6, 2003, at 10:53 AM, John Rodgers wrote:

> A a matter of good
> mechanical practice, the the torque values on bolts and nuts are
> established with no lubricants, and when a lubricant is added, it
> changes the parameters of the established torque for the part. So
> lubricants SHOULD NOT be added except where specified by the
> manufacturer.

WEB search results:
1: For greatest accuracy, use a thread preparation, either grease, 
lube, or an appropriate grade of Loctite, on the threads of the bolts 
you wish to tighten.

2: When using a torque wrench there are some basic preparatory steps to 
consider. First, make sure the threads of the fastener and the mating 
hole are clean and free of rust, dirt, carbon and goop. Debris in the 
hole or on the threads will cause galling of the threads and give an 
inaccurate torque reading. Secondly, if no special sealers or 
instructions are given for torque applications are given, use a small 
dab of high temperature grease on the threads and where the fastener 
head contacts the part. Use of this lubricant will keep the fastener 
from sticking and reduce the possibility of galling and stripping. In 
addition the grease will assure the proper tension of the threads to 
the mating parts when the correct torque is applied. It will also make 
the fastener easier to remove in the future.

Now you ask; why should I use an accurate torque wrench?� Well lets 
talk about torque and its properties. You see, nuts and bolts are held 
together by tension or elasticity. Some bolts are measured via stretch 
but we will discuss that issue some other time. Threads provide a 
continuously inclined plane, which creates a wedge for the bolt when 
you tighten the nut. Like a rubber band, metal is elastic, and will 
stretch a little as you tighten a nut. If you over tighten a nut you 
will go past the limits of the metal's elasticity and strip the 
threads. If you under tighten, the bolt will not stretch and thus will 
loosen more easily through normal use. A torque wrench allows you to 
tighten the bolt and nut to the correct tension, so it will stay in 
place without loosening.

3: Torque is simply a twisting or turning motion around the axis of the 
nut or bolt. Torque wrenches measure resistance to rotation. This 
resistance can be correlated to, but is not a direct measurement of, 
fastener tension. Generally, the higher the resistance to rotation, the 
greater the tension on the threaded fastener.

Typically, some type of lubrication is desired in the thread and at the 
bolt head. Without lubrication, a higher twisting resistance is felt by 
the torque wrench. The torque wrench reads only this resistance to 
rotation, it does not directly read the tension in the bolt. Be sure to 
check manufacturers suggestion on lubrication; many manufacturers 
require a certain weight of oil or other liquid.

Another option for thread preparation is a thread locking compound, 
such as from Locktite�, Wurth�, and Devcon�. This is a fluid that is 
applied to clean threads. The fluid provides some lubrication during 
torque. When sealed from air, the fluid hardens and expands as it 
cures. This provides resistance to loosening and also forms a seal to 
water and corrosion. Thread locking compounds can be useful when parts 
cannot be fully torqued. Thread lockers should not be used to replace 
proper torque and thread pre-load when clamping load is important. 
Generally, the service removable grades are used, such as Locktite� 
#222 or #242.

Cross threaded parts will cause more resistance than correctly aligned 
threads. A torque wrench is unable to distinguish this problem. Don't 
do something stupid and torque down a cross-threaded head bolt!� If you 
do, we're transferring you to a Ford group.

It is important to understand torque unit specifications. Be sure you 
read the manufacturers suggested torque requirements; remember, 125 
in/lbs is NOT the same as 125Ft/lbs!� Don't screw up and break 
something.

The most common reason for threaded fasteners loosening is simply that 
they were inadequately secured during initial assembly. Vibration, 
stress, or use/abuse usually will not cause a properly sized torqued 
fastener to loosen.
Now you ask; why should I use an accurate torque wrench?� Well lets 
talk about torque and its properties. You see, nuts and bolts are held 
together by tension or elasticity. Some bolts are measured via stretch 
but we will discuss that issue some other time. Threads provide a 
continuously inclined plane, which creates a wedge for the bolt when 
you tighten the nut. Like a rubber band, metal is elastic, and will 
stretch a little as you tighten a nut. If you over tighten a nut you 
will go past the limits of the metal's elasticity and strip the 
threads. If you under tighten, the bolt will not stretch and thus will 
loosen more easily through normal use. A torque wrench allows you to 
tighten the bolt and nut to the correct tension, so it will stay in 
place without loosening.