It's a pretty easy job to do really.
Best to remove bumper the night before, an give all bolts a good soak in wd-40 or any penetrating oil.
If you can reach or see the back of the bolt, get a wire brush (toothbrush size) and clean off any thread's showing and spray with oil. This save's dragging shit threw the threads as you undo it, also brush the heads clean so socket sits right. Any point while undoing bolts and they go tight, stop an wind back in and spray, then back out.
You prob know most of what i have said, but if the bar is looking worse for wear then the bolts will be in the same condition.
