I have 3 tractor attachments (flail mower, tiller, rotary mower,) with gear boxes, and they require 3 different grades of gear oil:
Flail Mower: 75W-90 synthetic
Tiller: GL-5 85W-140
Rotary Mower: SAE 90
I’m about to change out the oil in the rotary mower and tiller. The oil in the flail...