Full disclosure before I begin. . . I work for Loctite.
There are two main points in this thread. Regarding the original point of removability, there is only one reason bolts that are properly installed become difficult to remove later on and that is rust. I know it's hard for most people to believe, but in a typical threaded assembly, there is only about 15% metal to metal contact. (flights of the male thread touching flights of the female thread) The other 85% is air. Air which contains water and different amounts of salt depending on where you live. This is why we get bolts that are rusted shut.
Anti seize is primarily intended to prevent galling the threads as you install the fastener, especially with stainless steel parts. It is, as stated several places above, a lubricant. This keeps the male and female threads from welding themselves together (seizing) as you install. Secondarily, it remains in the threads thus preventing water from entering the threads, thus preventing rusting the threads together later on. The problem with anti seize is, that it always stays a lubricant. A lubricated bolt can more easily loosen both when you want it too and when you don't. The whole point of a torque specification is to apply a certain clamp load. You want that clamp load to stay constant until you're ready to disassemble the part.
There is a way to prevent water from entering the threads without leaving a lubricant behind. Using a medium strength threadlocker does lubricate the assembly process but it chemically changes into a hard plastic when it cures. Now you have a hard plastic filling up that 85% space. This does two things for you. It prevents unwanted loosening and also prevents rusting. So a thread locker is also an anti seize in the sense that it will take the same amount of torque to remove that fastener tomorrow as it will 10 years from now. Remember that the medium strength (blue) Loctite is removable with the same hand tools you installed with. However, if you're concerned about rounding over the heads of smaller bolts and screws, you can use the low strength (purple) Loctite. Same rust preventing benefits with lower removal torque needed.
Now, about the second topic. Torque vs clamp load for lubricated vs dry fasteners. FJ4068 is absolutely correct. It's too complicated to explain so I'll sum it up.
Torque is related to clamp load via a factor called "K"
The impossible part is that the "K" factor for any threaded assembly depends on the following:
1. diameter of the bolt
2. pitch of the flights
3. engagement of the flights
4. metallurgy of the male threads
5. metallurgy of the female threads
6. friction coefficient of the two metals describe above working against each other
7. quality of the fastener (i.e. how consistent are all the above from one end of the fastener to the other)
8. which particular lubricant? (by name and number)
So there's no way to tell you how much you should reduce A torque on A bolt. Believe me, engineers ask me that all the time.
However, if you're planning to put 30 or 40 thousand of the same nuts and bolts together and you can send me a couple hundred for testing, that's another story. That's how Toyota, and everybody else, comes up with the torque specs in the FSM.
So if I'm such an expert. . . how much do I reduce the FSM spec torque? "just a bit"
There are two main points in this thread. Regarding the original point of removability, there is only one reason bolts that are properly installed become difficult to remove later on and that is rust. I know it's hard for most people to believe, but in a typical threaded assembly, there is only about 15% metal to metal contact. (flights of the male thread touching flights of the female thread) The other 85% is air. Air which contains water and different amounts of salt depending on where you live. This is why we get bolts that are rusted shut.
Anti seize is primarily intended to prevent galling the threads as you install the fastener, especially with stainless steel parts. It is, as stated several places above, a lubricant. This keeps the male and female threads from welding themselves together (seizing) as you install. Secondarily, it remains in the threads thus preventing water from entering the threads, thus preventing rusting the threads together later on. The problem with anti seize is, that it always stays a lubricant. A lubricated bolt can more easily loosen both when you want it too and when you don't. The whole point of a torque specification is to apply a certain clamp load. You want that clamp load to stay constant until you're ready to disassemble the part.
There is a way to prevent water from entering the threads without leaving a lubricant behind. Using a medium strength threadlocker does lubricate the assembly process but it chemically changes into a hard plastic when it cures. Now you have a hard plastic filling up that 85% space. This does two things for you. It prevents unwanted loosening and also prevents rusting. So a thread locker is also an anti seize in the sense that it will take the same amount of torque to remove that fastener tomorrow as it will 10 years from now. Remember that the medium strength (blue) Loctite is removable with the same hand tools you installed with. However, if you're concerned about rounding over the heads of smaller bolts and screws, you can use the low strength (purple) Loctite. Same rust preventing benefits with lower removal torque needed.
Now, about the second topic. Torque vs clamp load for lubricated vs dry fasteners. FJ4068 is absolutely correct. It's too complicated to explain so I'll sum it up.
Torque is related to clamp load via a factor called "K"
The impossible part is that the "K" factor for any threaded assembly depends on the following:
1. diameter of the bolt
2. pitch of the flights
3. engagement of the flights
4. metallurgy of the male threads
5. metallurgy of the female threads
6. friction coefficient of the two metals describe above working against each other
7. quality of the fastener (i.e. how consistent are all the above from one end of the fastener to the other)
8. which particular lubricant? (by name and number)
So there's no way to tell you how much you should reduce A torque on A bolt. Believe me, engineers ask me that all the time.
However, if you're planning to put 30 or 40 thousand of the same nuts and bolts together and you can send me a couple hundred for testing, that's another story. That's how Toyota, and everybody else, comes up with the torque specs in the FSM.
So if I'm such an expert. . . how much do I reduce the FSM spec torque? "just a bit"