It is deffinately possible...
Possible to run a GM 6.5l on waste motor oil - with certain conditions met.
- injection pump - needs to be a DB2 or similiar, mechanical injection pump. Why - no electric 'photo' eye, which is an electrical sensor that views the fuel and can tell if it is clean or dirty, if it senses dirty fuel(diesel and WMO mix is viewed as dirty)it will tell the vehicle to shut down.
-Good idea to pull the screen off the pickup tube in the fuel tank, and replace it with a spin on filter head and filter, on the fuel line right before the 'Lift Pump'. Donaldson has a $20 filter head available and there are several fuel filters that one could purchase that pre-filter the fuel/water before going through 'Lift Pump'. Why - If your WMO mix is dirty then screen in tank gets clogged and is a pain to remove clean and install again. a spin on pre-filter is so much easier to replace lf it is on the frame rail near the tank and before the lift pump......