That would be a pretty interesting study. In testing I've done on brake caliper banjo bolts we've seen over 40% reduction in yield torque when the banjo bolts are lubricated with brake fluid compared with them being dry. In a nut shell it takes 40% less torque to fail the banjo bolt just by adding brake fluid into the joint.
That makes total sense to me. Some posters in this GJ thread and others, think they are being safer by just using a little oil on their lug threads instead of anti-seize. I guess they are assuming oil on the threads will change the torque requirements less than regular anti-seize does so it's safer. That is usually a wrong assumption. Like I said before, the regular anti-seize I use has a K factor of 0.18 so I need to reduce torque by 10% to have equal clamping force compared to a dry thread torque spec when used on lug threads. Pretty much everywhere I look, it shows I would need to reduce the torque more if I used oil on the threads instead, which means oiled threads will usually have a higher overtorquing risk compared to threads with regular anti-seize on them.
Here are the standard torque reduction factors that I have come across, sourced from multiple reputable locations online (like anti-seize manufacturer websites, engineering toolbox, etc.).
Two of the source links I drew my results from when I did my original work are still working-
Lubrication effect on bolt tension and torque.
www.engineeringtoolbox.com
For K factor calculations, dry bare steel threads (similar to lug threads) are said to usually have a K factor of around 0.2.
-Loctite threadlockers (purple, red, or blue only)- 10-20% torque reduction is what Loctite used to recommend, but now they recommend no torque reduction, which doesn't make any sense to me. Loctite makes bolts and screws noticeably easier to turn, so I usually reduce by 20% but I also don't use loctite very often.
-Permatex regular anti-seize (K factor 0.18)- 10% reduction
-Never-Seez High Temp Stainless- 13% reduction
-Never-Seez Nuclear Grade- 15% reduction
-Permatex copper anti-seize (K factor 0.16)- 20% reduction
-Never-Seez Regular- 30% reduction
-SAE 40W oil (K factor 0.14)- 30% reduction
-Permatex Nickel anti-seize (K factor 0.13)- 35% reduction
-SAE 30W oil (K factor 0.13)- 35% reduction
-Grease (K factor 0.12)- 40% reduction
-Graphite (K factor 0.10)- 50% reduction
If KnurledNut is still reading this thread, pizza grease mixed 50-50 with tobacco spit has a K factor of around 0.14, so a 30% torque reduction would be recommended.
