The oil will depend on the year and style of pumps/type of drive. As far as the performance of the hydro drives if they are to the point that they have no power to pull the machine or normal speed they most likely are severely worn, I am quite sure speeding up the pumps will not improve the performance or if it does it would be short lived. How many hours are on the machine if you have an hour meter or again what year is the machine. One possible fix would be if this is a older machine that has individual hydro drives with pumps and drive combo's on each side a possible oil change using the new Grasshopper Hydro Max fluid is enough sometimes to bring them back to life, make sure to change the internal filters between the reservoir and the pump. This worked for me on an older 1600 series some years ago.