The super 55 has thee 3 plugsd for the final drive. The front plug drains the transmission the second drains the center area and the rear plug is the rear drive part of the final drive. The gears sling oil to the front and keep the front parts full even though  the oil level plug shows low, to completely drain the oil remove all the plugs. The thick black oil is probably the old type oil used in the verry early tractors, {1920-1930&#039;s}  and probably will not completely drain until it is warmed up considerably. Someone likely put the wrong oil in the tractor. Hope this helps. Delbert