Cusser
+1y
I've had my B2200 18 years. I try to change it about every 30K miles.
I drain and then fill with Valvoline 80W-90 gear oil, and use the pump that screws into the top of the gear oil container. You should have a 23mm socket for this, and always loosen the fill plug (on any vehicle) before you remove the drain plug.
I use the same gear oil in my manual transmission as well.