If you are processing the oil to make biodiesel (the real stuff), pillowcase filter is sufficient prior to processing. Most of any suspended crap will fall into the glycerol layer during the processing. Water is slightly different. You need to get it out or it could screw up the processing.

Real Biodiesel and #2 will blend quite nicely and the percentage of Bio to #2 is what you hear with the Bxx designation. B100 is 100% biodiesel, and B60 is 60% biodiesel and 40% #2.

Once you finish making the biodiesel, even though most of the crap falls into the glycerol layer, you will still need a final filtration.

Real Biodiesel involves methanol and either sodium hydroxide or potassium hydroxide, reacted with VO/WVO at approx 130F. You will not make biodiesel any other way. (I had to add this as a number of sites are trying to confuse biodiesel with blended VO/WVO by calling their mixture 'bio-fuel'.

__________________
87 300SDL - 215K Miles !!
99 F-350CC Dually PSD - 190K
86 300SDL - 189K
All on B-100