Not Randy but I would use a good hyd non foaming fluid same as what is in the hyd sys, but dont see a problem using the 10w40, 20w40 or AW46 if you are having trouble with the hyd steering. I get my hyd oil at my local NAPA. I changed out all fluids after about 8 or 10 hrs, had to flush the radiator 5 or 6 times to get all the rust out. I have about 50 hrs on it now.
Walt