One solution to Polymerization is to remove the FFA from your WVA, the process is a bit tricky because you need to perform a process called titration. Once the titration is completed you know the level of your FFA. At this point you calculate the correct amount of lye and water to add to the oil it will create soap out of the FFA first then the virgin (read fuel ready) oil. You should be very precise (just like biodiesel creation) and you will have near virgin oil and a bunch of soap chips and bits.

Simply filter out the soap and leftover water, and wammo! you got yourself a bunch of virgin oil.

I use this for creation of Biodiesel as a step in cleaning the oil of the FFA because the FFA will not react in my processor. FFA can get as bad as 15% to 20% in WVO. And ALWAYS filter to .5 micron or better (just heat the oil to about 140 degrees F and push through a three stage filter system of your own make, screen 100 micron, sock filters for the rest).

In my humble opinion if you go through this process just make biodiesel and and you can run in neat even in the winter if you are already set up to run SVO/WVO. All the proper parts are heated already and at freezing biodiesel is gelled and liquid while SVO/WVO is a block of sludge.

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1985 300D Turbo 332k Miles (daily driver)
1987 300SDL Turbo 320k Miles (needs new head)
1968 International Scout 800 V8 119k Miles (garage queen two years and counting)
2005 Kia Optima (backup car) 36k Miles (accident )