I'm not inclined to argue with the specs in the FSM just yet. I don't have the experience. I have the feeling that if I would have used the Valvoline I would not have noticed any problems for a while if at all but I'd rather do what the manual says to be safe. I expect the Valvoline was ok for GL-4 differentials because they are all steel.

I just had the idea that I could spray a WD-40 or some brake cleaner into the open hole of the Backup light switch and maybe that would help the first 5/16 ball come out. I'm hoping I did not crush it in there. 4door I am waiting for a new switch when it comes I will hook it up and test it before trying to install it.

EDIT- Question, what is the correct procedure for installing the backup light switch? There is no mention of it in the FSM.