Dry vs lubricated torque
Lubrication lowers friction, so the same torque stretches the bolt further. Standard charts cut the torque by a quarter for oiled threads (nut factor 0.15 instead of 0.20) and by half for waxed nuts (0.10). Use the lubricated value only when the threads really are lubricated.
Sources checked
Why lubrication changes the number
A torque wrench doesn’t measure how hard a bolt clamps, only how hard it is to turn. The short-form equation behind the published charts links the two: T = K × D × F, torque equals the nut factor K times the bolt’s diameter times the clamp load. K stands for friction, under the head or nut and in the threads, and friction takes most of the effort: Fastenal’s bolted joint guide puts the share at about 90%, leaving about a tenth to stretch the bolt.
So a small change in friction makes a big change in clamp load. Oil, wax and anti-seize lower K, so the same torque stretches the bolt further; a thick, rough coating such as hot-dip galvanizing raises it.
How much the charts reduce it
For the same clamp load, torque scales with K. Against the dry value, that gives these settings, worked for a 1/2-13 Grade 5 bolt and an M10 x 1.5 class 8.8 bolt at 75% of proof load:
| Threads | K | Torque vs dry | 1/2-13 Gr 5 | M10 8.8 |
|---|---|---|---|---|
| Dry, plain steel | 0.20 | 100% | 75.4 ft-lb | 50.5 N·m |
| Zinc plated, dry | 0.20 | 100% | 75.4 ft-lb | 50.5 N·m |
| Oiled | 0.15 | 75% | 56.5 ft-lb | 37.8 N·m |
| Waxed | 0.10 | 50% | 37.7 ft-lb | 25.2 N·m |
| Hot-dip galvanized | 0.25 | 125% | 94.2 ft-lb | 63.1 N·m |
Nut factors from Portland Bolt’s and Fastenal’s published charts. The clamp load is the same on every row: 9,046 lbf for the 1/2-13, 25.2 kN for the M10.
What happens if you use the wrong one
Tighten a lubricated bolt to the dry value and it clamps harder than the chart meant, because less of the torque is lost to friction. By the same equation, a bolt tightened to the dry torque reaches:
| If the threads are actually | Share of proof load |
|---|---|
| Dry, plain steel | 75% |
| Zinc plated, dry | 75% |
| Oiled | 100% |
| Waxed | 150% |
| Hot-dip galvanized | 60% |
Oiled threads at the dry value land on 100% of proof load, the most the bolt can carry without stretching for good, with no margin left for friction scatter. Waxed threads would be asked for 150%, well past proof load: the bolt would yield, and could break, before the wrench clicked.
The opposite mistake under-tightens. Dry threads at the oiled value get 56% of proof load instead of 75%, and a joint clamped too lightly can work loose.
Which value to use
- Plain or zinc-plated steel, as received: dry.
- Oiled on purpose, threads and under the nut: oiled.
- Nuts supplied waxed, as some high-strength nuts are: waxed.
- Hot-dip galvanized: the galvanized value, which is higher than dry.
- Anti-seize or another compound: the K its maker publishes, in the calculator.
- Wheel nuts, and anything with a maker’s spec: the maker’s value, applied the way the maker says, which for wheels means clean and dry. See how to torque lug nuts.
Questions
How much should I reduce torque for oiled bolts?
The published charts use a quarter less: a nut factor of 0.15 instead of 0.20. A 1/2-13 Grade 5 bolt goes from 75.4 ft-lb dry to 56.5 ft-lb oiled for the same clamp load.
Do zinc-plated bolts count as dry?
As received, yes: the charts use 0.20 for zinc-plated steel, from published values of 0.17–0.22. Oil or wax on top of the plating makes them lubricated.
Does anti-seize count as a lubricant?
Yes. Anti-seize and other thread compounds lower friction just as oil does, so a dry torque value over-tightens. Use the nut factor or torque the compound’s maker publishes; the calculator takes a custom K.
Should I oil lug nuts?
No, unless your owner’s manual says to. Kia’s manual says never to use oil or grease on the wheel bolts or nuts because the nuts might come loose, and Mazda’s says the same. Wheel torque values are for clean, dry threads.
Sources
- Fastenal: Torque–tension relationship for A307 A, Grade 5, 8 and 9 coarse thread bolts (75% of proof load; K 0.15 and 0.20) (checked October 14, 2026)
- Fastenal: Torque–tension relationship for metric fasteners, property classes 4.6, 8.8, 10.9 and 12.9 (checked October 14, 2026)
- Portland Bolt: Bolt torque chart: T = KDP at 75% of proof load, with K for plain, waxed and galvanized bolts (checked October 14, 2026)
- Fastenal: Bolted joint design: nut factor (K) by finish and how much preload varies at a given torque (checked October 14, 2026)
- Kia: Telluride 2022 Owner’s Manual: Changing tires (checked October 14, 2026)
- Mazda: 2025 Mazda CX-50 Owner’s Manual: Changing a Flat Tire (checked October 14, 2026)
Spotted a number that doesn’t match your manual or a source? Tell us; corrections are logged on the sources page.