Adding hydraulic fluid to 1950 ford 8n same as transmission and gear oil for these tractors. Sep 05 2020 by c s lewis read how to drain hydraulic fluid from 1952 ford 8n get a drain tub pan underneath the differential case and using a 9 16 open end wrench and the ford plow wrench or a 1 1 16 wrench first loosen the diffy drain plug with the 9 16 open end wrench you need an open. Cleaning out the hydraulic sump by carl schmottlach 51 8n nellie if your tractor will run then the first thing to do is to start it up and run it long enough to warm up the engine and the fluids you also need to lower the 3 point arms to their lowest point this changes something inside the pump that lets the fluid drain more fully