It is my understanding that the transmission and rear end on my Oliver 770 is supposed to be filled with 10w-30 motor oil. When I bought this thing last summer it had about 10 gallons of water and 1 pint of oil sludge in the system. I drained it and filled with diesel fuel and operated around the shop for about 10 minutes and then drained it. Out came rusty diesel and some more water. I obtained 10 gallons of used but fairly clean ATF, filtered it to remove any particles big enought to have part numbers on them and and poured 5 gallons into the transmission. I operated the tractor again for about 30 minutes this time. I drained the ATF and filled it with the other 5 gallons of ATF and drove it up and down the road about 1/2 mile. I parked it under the shed area of my shop for the winter. Saturday I took the rear end cover off and had me a look. There was some rust pitting on the bull gears and pinions. A little on the ring gear but none on the pinion of the differintial. I dranied the trans fluid and and flushed it with some gasoline to remove all traces of the remaining dirt and water. Upon refill I had 2 gallons of 90W and a case of 30W motor oil. I used the 90W and then another 8 quarts of the 30w engine oil. I then bush hogged an acre of grass. I noticed that prior to all this I had to grind the trans into gear and the trans had a whine to it. Now it shifts fine with very little or no grinding. The transmission is MUCH quiter now too. I figured the high viscosity of my oil mix is adding enough drag to stop the gears from free wheeling so much. Should I drain this out and replace with the lighter oil or keep what I have?
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