What is the best oil for the transmission on the TO-20 right now? I am using 30W motor oil in both engine and transmission. October 10, 2014.
The correct oil for the transmission/rear axle/Ferguson system is SAE 90 weight mineral oil. You can purchase it in 2 gallon jugs at Tractor Supply Stores. Ask for “Traveler Ford Tractor All Mineral 90 Transmission Fluid” SKU #0806600.
You will need just under 6 gallons or 3 jugs to change the oil. Make sure you push the hydraulic control lever down to drain the lift cylinder and remove all 3 drain plugs, transmission, hydraulic pump, and rear axle housing to drain the oil. Oil is added at the plug on the top of the of the transmission, shift lever cover. It will take a while for the oil to flow to the rear housing so keep adding a little at a time and rechecking the level after you have added approximately 5 gallons. Then run the PTO, raise and lower the lift arms several times to make sure the pump and cylinder have oil in them and recheck the level.
This information is contained in the operators manual which is still available from AGCO/Massey Ferguson. The original factory service manual and parts book are also still available. You can order these manuals on line from AGCO/MF. If you need additional information, please let me know. 30 weight motor oil is correct for the engine for warm weather operation.