tub grinder oil

i purchased a used toro progrind 2000, machine had not ran for sometime, got it running and seemed to work great when we tested it. then we went through and changed all the fluids. manual says you can use phosphate ester oil or mobil dte 24 in the fluid coupler, after putting the mobil product in it blew out in less than 2 minutes. after talking to the engineer he said that i can only use phosphate ester, does anyone have experience with this and know where a person can get it, i believe i have found it but in 55 gallon durms only, i need 5 gallons

tub grinder oil