Wd-40
I will add to what Quexpress says, with a addition, if you have any penetrating oil with a extension, like used for chain lube, get in and spray past the bolt head. What I am going to tell you I have used 10000 of times. A common problem with alloys, stainless steel etc. is galling , that is when some of the threads become embebed into the harder material of the bolt. What you do, is say every half tun, spray your penetrating oil in, but go 1/2 or 1 full turn clockwise , what this does is help lube the dry thread you just freed up, it helps overcoming red loctite , so at 3 full turns out, go back 1 turn and lube, you will be surprised at how much easier that is. Last if you are concerned of the new bolt and mount coming loose, use brake cleaner on the bar thread, allow to dry, use blue loctite sparingly, 3 threads maximum. The vibration spoken of is like a impact , one last word, if you reach a point that the force required is double what you have been applying, STOP, spray and try turning back in possibly 2 or 3 turns, spray again, it may take 2 tries , you don't want to twist anything off.