Once went on a torque course at work about 15 yrs ago at a place called “christie” and think it was Leeds way, they showed us all sorts of variations in torque complications when using added “lubes” they suggested using no lubes in most applications or if you “had” to, then only a very light oil. A big no no in their opinion, and they proved it, was to never use copper applications or grease. With these added to threads you have to increase the torque given to reach the recommended required torque needed for said fastening to do what it is required to do. For example, they had two large 10mm thick pieces of steel about 2 foot by 1 foot square with holes all the way around the outside. To demonstrate they firstly started with fresh dry un-oiled/greased bolts, and just torqued them one by one in a clockwise rotation to the same torque on each. (We all know they should of torqued opposites or to a set sequence but they did it this way to highlight what actually goes on in the day to day out there in the real world with us human beings) Typical example being to compare what happens when you remove and refit a wheel. Once the plate was torqued they offered up a debate on what would happen next when we went back to the first bolt? This passed about 5 mins of time. He went back to the first bolt and it clicked off at the same torque as initially tightened too. Next trial was role repeat but with grease added to the threads, “cos we dont like seizure in our world do we” he said. Torque sequence repeated, all the way round one by one in a clockwise direction, then again next up was the debate...... what happens when we go back to number one?! I was gobsmacked at the outcome!!! Every bolt moved, and not just a little, but a lot!!! The grease disperses under pressure slightly and so the bolt becomes no longer fully tight. They also said this is a major issue when using dedicated stretch fasters (stretch bolts, one time application bolts) this being because, when you tighten the stretch bolt to say 100NM or whatever, to achieve 100NM a the mating surfaces of your bolt and work piece you actually need to apply more than 100NM of force, otherwise the bolts will not be fully tight due to the grease as stated above, so to make it achievable because you are having to force the grease out of the way on all your threads, using more than 100NM recommended force, this in turn takes the bolt past its “elastic limit” therefore becomes..... stretched and unable to achieve its goal. They recommend using the lightest oil possible in all applications to reduce the amount of friction that is produced on the threads that could end up giving the over torquing scenario. I still personally use oil/grease/copper etc myself because i work in the real world as you guys do, and we like things to come off/undone again but it was a real eye opener for me, and so every time i do a torque on anything i ensure i go opposite every time and if i use anything above an oil, grease/copper etc i try to use least amount possible and torque up with a little extra nudge [emoji6] (rightly or wrongly) and for one time applications they get a dusting of tipping oil from my squirty can, nothing more. Only cos i dont like things dry of course! [emoji4]