Link: http://adteputek.com/b2evolution/blog2.php/2009/06/29/why-use-threadlockers

This variety is useful for all types of metallic fasteners to prevent their loosening due to shock and vibration. It can be used instead of conventional locking mechanisms like lock nut, spring washer, nylok nut (nut with nylon insert), tab washer, split pin, etc. The product also seals threads in addition to locking and prevents thread corrosion. Because of this advantage one could avoid seizing, the problem of removal at a later time.