You should filter the oil. If you have a NAS 3 and NAS 1 is desired, a filtering chain should be designed. For example one 20 microns 95% efficiency filter first. second 15 microns 95% efficiency second and 10 microns eff 99%. This last filter wil be clogged very quickly at the begining, it should be replaced several times.
In the filtering process, viscosity and temperature are the key properties. Water content should be reduced as much as possible in advance to filtering.