I am glad this subject came up because it is also a concern to me. My vehicle is almost finished with a wvo kit but stopped when doing some resurch on the subject. My worry is the free fatty acids and water would "etch" the insides of the IP over a period of time. I have also made biodiesel before a few years ago and still have the sample. The oil was originally very dark which means it had free fatty acids in it. Now finding a good batch is important if you are going to run strait wvo. I have a ph tester to test it and reject it if the owner does not change it often enough. So in a case like this I can be picky. What I have not seen how how many kms or years has somone run wvo and there IP,injectors,cylinder walls survived? I dont have 1,200 dollars for a rebuilt IP so dont want to take any risk associated with this setup. Just wanted to mention about the person who had the blood poising. If you are making bio please seal the container so not to breath the methaloxide solution. It will render you blind.