I just use paraffin in mine. Its every bit as good as the proper fluid Ive used in commercial premises in the past, and the plus is it leaves a thin protective oil film on things so they don't start to corrode instantly.
Caveat is that you have a big drum of fluid that will burn readily in your workshop, thus should treat it with care, and its not too nice for your skin, so either barrier cream or gloves or wash after use...
Oh and don't drain the paraffin off and use it in the shed heater when its cold, cos it stinks of old oil!
Try Desolvit. Its the recommended fluid for flushing Land Rover intercoolers so should be available form dealers or motor factors. Failing that then Gunk ot Jizer from the factors both of which are water soluable.
Chris