but how do i oil the rosewood fb? can i oil the rosewood fb with the old strings on and then change the strings one at a time like i usually do. That way the setup/etc remains unchangedI usually start taking off springs, one at a time, as I remove the strings. Eventually, I can just lift the bridge out altogether.
Another option is to change the strings one at a time. That's perfectly valid. Makes it a bit more of a hassle to oil the fingerboard (even trickier if you want to clean it), but it's still doable.
A third option is to block the trem with a piece of wood or some such. That will hold the trem in place.