My R150F (5-speed manual) transmission is hungry for gear oil?

[brocktice]

I just drained the oil that came in my 1994 T4R's manual transmission (dirty and black, probably from my missing shifter bushing disintegrating).

I had a gallon of MT-90, which per the service manual should have been more than enough, and I pumped it all in there, but it wasn't enough to make it run out the hole. Everything I've read says it should be up to the hole at around 2.5L.

I can't actually check the level with my finger because something is in the way (maybe because I park it in reverse, I'll try moving the shifter).

Any thoughts on where that extra fluid went? Should it be OK to drive to the store and get more (about 25 highway miles round trip)?

Thanks, and happy Thanksgiving to the USians here.

 

[brocktice]

It appears what I thought was the fill plug is labeled 'non-reusable part' in the FSM. Uh, whoops. What is it? On the passenger side above the drain plug. Takes a 10mm hex bit.

Oh wait, that's the drain plug crush washer. I have no idea what the hex bit part is.