I am planning on using the same existing gas tank on my GTI when I put the diesel engine in. Does anyone know of there is any compatibility problems with the materials used for the gas tank, and biodiesel? Some people (of questionable actual knowledge) have told me that even regular diesel will eat the lining out of the gas tank. There will be a separate plastic fuel tank for the veggie oil (which often has water and other weird stuff in it), and only ASTM biodiesel or sometimes regular diesel will go in the existing fuel tank.
Zeke
yes questionable actual knowledge.
diesel and gas tanks are identical in rabbits/jettas/caddies.
flush and refill
yes questionable actual knowledge.
diesel and gas tanks are identical in rabbits/jettas/caddies.
flush and refill 
I thought they were the same (except for different diameter filler doors) Thanks.
Z
the fillers are different for sure. the tanks themselves are the same.
how about the rubber filler pipe?
I bet that rubber hose between the filler and tank will be destroyed by biodiesel .... but I don't know what to replace it with.
would silicone work? i know of a marine store that sells silicone reinforced tubing made for wet diesel exhausts.