So Future Heap Owner’s recent rustventure has me reconsidering the use of anti-seize on lug nuts...
We touched on this subject earlier when I shared John Cadogan’s lengthy videos on the matter. To sum up, he reasoned that there’s a wide safety margin of safe torque, that the use of thread and/or seat lubricant doesn’t screw up torque readings enough to worry about, and that the important thing we should be focusing on anyway is using a torque wrench instead of going crazy with the rattle-gun.
Now FWIW, despite living in a salt state, my habit thus far has been not to use anti-seize on lugs. Sometimes I do see it already applied to a car, but I don’t bother to clean it off because I appreciate the assurance that the threads won’t be locked up. But somehow I’ve been getting along just fine without it myself...
I was thinking that maybe the deciding factor was going to be the use of capped lug nuts (or hub caps that completely cover the lugs from the elements), but the pictures in FHO’s post are making me doubt that. I mean, those studs are definitely rusty, right where the nuts go, and the capped nuts didn’t seem to help prevent that.
The fear that the lubrication will make it too easy to overtorque the lugs is perhaps the most popular concern when it comes to using anti-seize here. And many service manuals come with explicit warnings against lubricating lugs. My Sierra manual states the following:
Notice: A torque wrench... must be used to ensure that wheel nuts are tightened to specification. Never use lubricants or penetrating fluids on wheel stud, nuts, or mounting surfaces, as this can raise the actual torque on the nut with out a corresponding torque reading on the torque wrench. Wheel nuts, studs, and mounting surfaces must be clean and dry.
Hm. I hope that the “mounting surfaces” are a reference to the fastener seats, because I can’t imagine lubricating the face of the hub or backside of the wheel would be problematic. In fact, my Mustang’s service manual’s warnings are phrased a bit differently, recognizing the need for preventative measures against rust:
Corrosion buildup can result in wheels sticking to the axle or rotor flange after extensive service...
Coat wheel pilot area with Disc Brake Caliper Slide Grease... or equivalent meeting Ford specification... Do not apply grease to lug nut seats or wheel hub bolts.
Here’s the kicker, though. While Ford does say not to use “grease” (which might be a specific reference to the aforementioned “Disc Brake Caliper Slide Grease”) on the threads, they do apparently permit careful use of a “graphite-based lubricant”:
It seems to me that lubricating only the first three threads allows the nut to carry only a very small amount of lubricant to the nut’s final position. So little in fact, that Ford’s recommended lug torque spec of 85-105 lb-ft is left unchanged.
So it would seem that lubricating lugs can be an acceptable practice after all, depending on the type of lubricant used, and the technique of application. There might even be a proper way to use regular anti-sneeze, despite manufacturer warnings. Maybe they just didn’t bother taking the time to study a safe method of using it, to include in the manual.
Now that I actually take the time to google it, this page claims that you should undertorque a lubricated faster by 30%; 40% if using SAE 30 oil. As for anti-seize in particular, this document from AST Industries advises that when using their product, you should aim for an undertorque of 25%. Curiously, Permtex’s technical data sheet states to “reassemble parts using normal torque values”, implying that their “refined blend of aluminum, copper and graphite” has a negligible effect on torquing.
This may reflect an inconsistency in their testing methods. Or perhaps we’re comparing apples to oranges formula-wise. How deep does this rabbit hole go?