Hello toydiesel01,
                      I was lucky enough to acquire a centrifuge and heater unit from asmall power station, and have been trying to clean up some drums of WMO recently.
My unit appears to exert about 6500 X gravity, which seems to be about 3 times that of many small units offered to the home market. Even at this force and 70c preheat
I am recirculating a 200 litre (50 gal) drum for 8 or 9 hour till I cease to collect signifigant amounts of carbon. The oil still remains black, as I understand the remaining carbon is
finer than  1 micron, and probably not harmful in a fuel blend for precombustion type diesels. Power usage is a factor depending on price, asI run near 5kw of 3 phase power
for round 8 hours (40 kwh) to clean a drum of oil.
         An experiment with about a 10% blend with diesel in an older direct inject motor had the injector tips badly carboned up, and smoking badly after about 20 hours on
load. Luckily pulling the injectors and brushing off the tips restored performance.
        I presently run about 40% WMO, 40% diesel and 20% Jet A1 in my IDI (precombustion) vehicle and it starts well and burns clean in our warm climate,but I will continue
to try various blends with caution. Jet A1 seems a very acceptable thinning agent for heavier oils, including waste cooking oils,(at least in our climate,  Regards,  Combustor.