I'm trying to change out the lubricant, but I can't get the bloody fill plug out. I don't want to proceed until I do. I'm pretty sure I have the correct location, but maybe I don't. What I'm trying to loosen is on the face of the differential facing the front of the car, about half-way up, on the drivers side. The only tool I can fit in the square hole is the drive for a 3/8" wrench. I've sprayed a couple of times with WD-40 and I'm about to go down and try again (waited about 20 min. now). Am I missing something here, I'm afraid to torque much harder for fear of stripping out the square hole