Sling it in mate!!!!!!!!
I've ran my 96' Maverick (Zexel) and '04 Terrano on Waste Oil, New Oil and at the moment homemade BioDiesel that I'm making using waste oil from various restaurants and take aways :thumb2
Learning from past problems, and this is only my opinion, I have removed the OEM fuel filter setup as I like to see whats going on in my filters I use clear plastic bulb ones (5 Microns) and replace the feed and return lines with clear food grade PVC pipe (I have some pre cut lengths for sale if you are interested)
I've ran pure oil straight out of the 20l tins down to temps of about 3-4 degrees before you see a noticeable behavior difference in idle at cold etc and sluggishness, at this point I usually just throw some Diesel/Petrol in but this year I'm going to try and Winterize my BioDiesel the right way with additives :thumb2