"Well, I’ve made a significant change to my WVO design. My original plan was to have 2 seperate fuel tanks. The first would contain regular petro diesel, and the second tank would have WVO with a heat exchanger (see below). With this plan, the vehicle is started on the diesel, and once the WVO has warmed up to coolant temp, the fuel path is switched to start injecting pure veggie oil. On Sunday I ran some viscosity experiments in the lab, and found that by blending diesel and WVO together, I can pour the mixture into my single existing tank and run it direct. I started with a 25% WVO/ 75% diesel, and found it ran quite nice. [...]"

http://www.mainelife.net/1982-vw-vanagon-wvo-convers...