Scale Evinrude Lower Unit Greasing

[BanjoBoatMan]

I have a couple of OSE's Scale Evinrude outboards that I have installed on a much modified Dumas SK Daddle. The build is going very well--need to make some ballast adjustments with the ESCs, but overall pretty satisfied. Attached picture was taken before rotating radar unit was installed on the top of the radar arch.

Question: how to keep the lower unit greased? Steven from OSE suggested adding grease from the top, which makes sense. But I am wondering if that is what the plastic tube inside the unit is for. Is this tube used for adding grease to the lower unit? Thanks.