What Wayne said. You’re thinking WVO (waste vegetable oil) You have to hack the car basically to get it to run properly thus decreasing it’s value immensely. Plus they usually have huge mileage.
There are different grades of Biodiesel ranging from B2 (2% soy or other similar) up to B100 (100% soy…) There are advantages and disadvantages to it of course but it has FAR superior lubricity in comparison to regular D2 ULSD. I recommend everyone run at least B2 just to keep your pumps and injectors lubed and in good shape. I’ve read several diesel additive tests that compare lubricity and B2 Biodiesel out-performs all of them.
In the new common rail TDI’s like mine, per the owners manual I can only run a max of B5 or less to keep my warranty, so that’s what I’ll run.