May I add my $.02? If one studies at a quality torque chart many answers can be found about this subject. To start with the function of a threaded fastener (bolt) is to hold an assembly of parts together under tension, bolts do this by stretching slightly when tightened. The job of the mechanic is to judge the proper stretch for a given fastener so it can properly function with out failure. There are many ways of measuring this but the easiest way is to refer to a torque chart. Given the size, thread pitch, quality and wether or not, and with what, a fastener is lubricated with a torque chart will translate rotational force (torque, usually measured in pounds/feet or pounds/inch) into the proper stretch for the bolt. There are three columns of torque values per fastener and each column lists a different value for the given size and thread, and since a fair amount of the rotational force applied is used up over coming the friction generated by the threads working against each other there is a column for dry, one for lubricated with oil and one for lubricated with moly grease. Each value compensates for the frictional loss generated by the varying degree of lubrication or lack thereof and gives us the correct amount of stretch. What this all means to us is that we can properly tighten a bolt with considerably less torque when using a lubricant, such as motor oil or grease, and as a rule of thumb a bolt lubricated with oil requires 75% as much torque as when dry. And if you use a high moly grease such as "High Temperature" or "Disc Brake" grease you can reduce the dry figure by half (50%)! As an example a 1/4-28 grade five bolt will be properly tightened at 10 lbs/ft when dry, 7.5 lbs/ft when lubed with oil and 5 lbs/ft when using moly grease. My recommendation is to always use some form of lubricant on all bolts and threaded fasteners, and understand that the required torque will depend on what type of lubrication is used. Motor oil is a fair fastener lube and easily available, although a little messy and hard to apply in the small amount required. IMHO a better lubricant is Lithium (white) grease, it is reasonably water resistant, stays where you put it and is somewhere between oil and high moly grease in lubrication ability. Anti-seize is intended for exceptionally high temperature applications where a grease-based lubricant will oxidize (burn) away before the fastener will be removed, hence the term Anti-Seize. Also, Anti-Seize has about the same lubrication value as oil. When drawing up alloy crank arms use a very thin film of white (lithium) grease on the tapers of the spindle, a small amount of same on the threaded area of the bolt and just a dab under the head where it touches the crank arm.
Scott "Torque Value" Mattern
>From unseasonably warm Hacienda Heights Ca.