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Don’t lube your lug studs!

Another example of “Don’t believe anything you read on the Internet” is the ongoing argument on whether or not you should use lube on a lug stud.  I say this as a guy that had to go out in the field an rescue vehicles that were sitting with all their stud sheared off, but there is so much mis-information on this that I’ve put together a handy source from the actual authorities on the topic of wheels and drivetrain components.  Virtually every time this topic comes up, some variation of “We’ve always done it that way” comes up, which is a classic, easily identified logical fallacy “Appeal to Tradition.”

If the following doesn’t work, for you, remember another rule: “The first rule of Dunning-Kruger Club is you don’t know you’re in Dunning-Kruger club.”

 

I think I’ll lead off with a widely known reference to tires and wheels–Tirerack.com:
“Torque specifications are for dry threads only. The fastener threads should be free of oil, dirt, grit, corrosion, etc. The hardware should turn freely without binding when tightened by hand. It is important NOT to lubricate hardware threads or seats. The friction at which torque is measured against should come from the hardware seats. Lubricating hardware threads and seats alters the friction generated at the lug seat which will result in inaccurate torque readings and/or over-torqueing of the hardware.”

A Industry trade journal, Auto Service Professional:
“Applying oil, grease or moly to the threads will result in inaccurate torque values (you’ll end up over-tightening). Simply make sure the threads are clean and dry. “

Ok, everyone knows who Hotrod Magazine is:
“Using oil, grease, or antiseize lubricants on the threads will give an inaccurate torque reading that will cause the lugs to be overtightened.”

I hate to cite this as a reference, since it is a forum, but “Bob is the oil guy” is pretty well known, and it cites many external verifiable sources.
quote:


NEVER USE LUBRICANTS OR PENETRATING OILS ON WHEEL STUDS, NUTS OR MOUNTING SURFACES, AS THIS CAN RAISE THE ACTUAL TORQUE ON THE NUT WITHOUT CORRESPONDING TORQUE READING ON THE TORQUE WRENCH. WHEEL NUTS, STUDS AND MOUNTING SURFACES MUST BE CLEAN AND DRY. FAILURE TO FOLLOW THESE INSTRUCTIONS COULD RESULT IN WHEEL, NUT, AND/OR STUD FAILURE


From a 2002 GM service manual

T3 Technique is a manufacturer of suspension and drivetrain axle parts for Vanagons.  They spend a LOT of time on this–the topic extends over a full page, but I will quote just this one part, however if this isn’t enough to make the point clear, I encourage the reader to read the entire sheet.
“If you were to add any sort of lubrication to the threads and the head of the fastener, the amount of friction between those two areas will be reduced during torquing which will translate to more of the torque value being applied to the threaded/shank area of the fastener. In other words, let’s say that you reduce the friction between the head and the threads by 20% by adding lubrication. This means that now only 65-70% of the torque value is being used to overcome friction and 30-35% of the torque value is applied to the threaded/shank area of the fastener. This would result in a fastener that is over-torqued by roughly 20%, which could result in the fastener reaching plastic deformation and therefore rendering it unsafe for use. “

 

As the name would indicate Fleet Owner is a trade journal targeted toward the over-the-road trucking fleet owner industry:
“If that isn’t enough, stud-piloted wheel systems require a dry torque, so the use of a lubricant like anti-seize will result in more pounds of clamping force per foot-pound of torque. Among the results are accelerated rates of stud fatigue and ball seat wear. So anti-seize decreases the service life of both the stud and the wheel.”