The level check for the hydraulics/transmission/rear axle is pipe plug on the left side of the tractor just in front of the rear axle housing. Oil is supposed to be at that level with all hydraulics extended.
8 litres (divide by 1000)
Looks like the going rate for a Model 3020 is about $8000.
As far as I know a 6520 weighs around 8,000 lbs [or 3628 kg].
This would be 8000 because you would round down.
Should be listed on the master cylinder cap. I would suspect it takes DOT3.Use Ford brake oil spec 1Q-M6C34-A
8000
10% of 8000= 10% * 8000= 0.1 * 8000= 800
8000
13% of 8000= 13% * 8000= 0.13 * 8000= 1,040
2% of 8000 = 2% * 8000 = 0.02 * 8000 = 160
20% of 8000 = 20% * 8000 = 0.2 * 8000 = 1600
58% of 8000= 58% * 8000= 0.58 * 8000= 4,640