T.O. 35 Oil Questions

Hey guys I need some help. I usually only work on old two cylinders and have the books for my tractors. My dad has a T.O. 35 he bought last year and uses to mow his yard and blade his driveway. Long story short he asked me to change the oil in it today and I drained it and put a new filter in it. How many quarts and what oil do you run in these? Also in the process I checked the dipstick on the rear end and it was way too full and looked as if it has got water in it. So I pulled the plug and drained it, I also noticed another plug in front of it under where the dash would be and a large diameter cap. I pulled that cap and oil looked the same so I pulled the plug and drained it. I left plugs out and told him to let drain for a couple days and put some diesel or kerosene in it to clean out and let it drain for a couple days. My main questions are #1 What type oil should go in the fill hole below the dash and how much? #2 Where do you fill the oil for the hydraulics and what type should we use? I saw a cap that looks like where it should be filled however it seems awful small for a fill hole. I have attached a pic of the tractor... Thanks in advance for all the help...

You have 2 excellent choices. Above is the Massey -Harris- Ferguson Forum, to the left on the grey bar is Harry Ferguson forum, your dad's tractor was made by one of these, but the specs for all gasoline engines are the same. But, some of the masters on these forum have different ideas on which hydraulic/motor/gear/mineral oil to put in the back filler.... 8 US gallons of...??? go ask up there... serial number or year if you know it helps 'em help you. see ya there.