I have 3 torque wrenches, each with a limited range. I somehow intuited that a torque wrench isn’t necessarily accurate at the low end.
Excellent. You most likely have the right tool for the range you are working in.
I don’t doubt what you’re saying, but it begs the question why the people who wrote the owners manual would advocate for torque values for the dry scenario or the other reasons you mentioned and not take the wet threaded version into account. I’ll defer to your greater practical experience. I’m just a somewhat talented classically trained singer (among other things) who is trying to save money and also trying to do a good job of turning wrenches.
I can't speak for all situations, but what I've seen first hand is that the engineers spec the torque spec based on the size of the fastener, for when the product is being built, (dry). The technical writers then look up that spec and re-use it in the manual. In far too many cases, the engineers never have an opportunity to review the manual before it is published, that not being their end of the project. Sometimes the manuals are actually published before the product is even finished and finalized, which can create some interesting nightmares for customer service later. BTDTGTTS
The most commonly stripped out threads on vehicles are spark plugs and drain plugs. Followed by small fasteners being snapped off. Even skilled and experienced workers sometimes run into things not commonly experienced in their normal work and get bitten by this. A heavy equipment mechanic used to using a 1000 ft/lb torque wrench sometimes has no idea what 50 in/lbs feels like and snaps off the fastener or breaks the torque wrench w/o realizing they instantly exceeded the torque spec before breaking things. I have watched people grab a in/lb torque wrench with their entire hand, then brace themselves prior to getting ready to pull the wrench. I stopped one and showed him how two fingers were enough for 50 in/lbs. He just had no frame of reference prior to that. He had already broken two of my in/lb torque wrenches that day, having had to borrow them because none of his normal work required that low range.
