Lots of opinions out there. do put some serious thought to it. If you do use WVO it needs to be impeccably clean. many times used oil also needs to be warmed as being used. Do do your reading beforehand. I have used K-1 before mixed with diesel but it is a distillate.
Good Luck but please let us know the results. I think many will find this interesting.
In my B7100, Iv'e tried new rape seed oil at 50:50 mix with derv which is what I run my VW 1.9TDI on and it runs ok but there are too many other things like water and insoluble fats in untreated used frying oil!
Dave