PTO help

[Deepwoods1651]

I changed the fluid in the rear end. I used Mobil fluid 424 tractor hydraulic/trams fluid. After that when running the PTO will slow down like it is slipping. Not sure if that is the right fluid or not. Any advice would help. Love the little tractor but it is just too slow to use. I have tried to run it in all 3 gears on the PTO and it Boggs down in all gears.the tractor motor stays at the same RPM.