The fuel line in the Rabbit looks fairly new, with the exception of my return line. If I were to just replace the return line, can I use standard FI hose or do I need a special diesel hose?
OK, I am an engineer - so take this with a grain of salt...

Reasoning, return line is lower pressure, and diesel is less caustic than gasohol.
SO if it were me I'd use the FI line....
BUT I am sure that I am an idiot for some unknown reason to someone else who will pipe up in a minute...
If it were mine (hummmm) and I had FI line I'd use it.
KC