Importance of Bolt Application

Are there any advantages to using lubricants for bolt tightening?
"If fixed objects do not slide against each other, lowering the friction coefficient is beneficial in all aspects. If fixed objects are in a "loose environment", if the friction coefficient is low, they are more likely to loosen, but it will not necessarily lead to loosening.
 If they repeatedly slide against each other with a force that exceeds a certain threshold, they are in a "loose environment."
 How do external forces cause slip based on shear direction, axial direction and torsion?
"If an external force is applied in the shear direction, it will cause sliding. If it is applied in the axial direction, the fixed objects will separate from each other - separate. Under these conditions, the lower the friction coefficient, the greater the possibility of loosening.
 While writing Bolted Joint Engineering - Fundamentals and Applications, I used the traditional view of sliding phenomena to explain the sliding of fixed objects on contact surfaces - the so-called "macroscopic sliding". You can observe with your eyes as this type of sliding requires only 0.1 mm for visual confirmation. Around 1988, it was discovered that invisible "micro-slips" actually occur before sliding and cause rotation, which is microscopic and cannot be confirmed with the naked eye, whether it is turning in the loosening direction or not. This "micro-slip" phenomenon gradually reduces the axial force.
 If fixed objects are in contact with each other, traditional experiments cannot measure the amount of sliding on a part of the contacting surface or other parts. But all these values can be calculated using the finite element method FEM. It has been used in the fastener industry since around 2000, and most threaded fastener research today uses it.
 Announced in 2006 the discovery that gradual rotational loosening occurs with microslip (invisible tiny slippage) rather than macroslip (clear, visible slippage). I was shocked when I first read this article, which stated that when microslip occurs repeatedly, it can cause tiny rotational looseness as small as 1 degree every 1000 times, or 1/1000th of a degree each time. The 1/1000th degree of rotation is not observed at all by the eye. Using the finite element method it was perfectly possible to study it and prove that micro-slip can lead to rotational loosening. I thought I was in trouble! The results shook the concept of critical slippage to its core.
Fact: Microslip
 Sliding is not visible to the naked eye. Gradually reducing the clamping force will eventually lead to visible rotational loosening (macro-slip). Settlement and relaxation of material can also reduce clamping force. Nord-Lock Group has developed the X-Series washers to handle both forms of slip. They counteract various clamping force losses through the spring effect, while the wedge effect prevents spontaneous bolt loosening.