Engine = 2006 honda 150hp with 235 hours, Product ID = BANJ-1200165

Issue #1 = the Gear Oil Leveling Plug screw (the top one) does not stop tightening. It is extremely tough to turn but I can still tighten it by hand. On other outboards I have changed, the screw eventually stops turning and I know it is sealed. The screw has an o-ring that I did NOT replace. The gear oil drain/fill plug acts as I would expect, it tightened right up and stopped moving.

Issue #2 = did I use the wrong type of gear oil? From Napa, I picked up Sta-Lube, SAE 80W90, API/GL-5, Hypoid. Will this oil be OK? Will it foam up on me?
Thanks