I replaced my fuel lines earlier this week with viton hoses cause I use biodiesel. These lines have lasted for a year going 8000 miles on B100. After looking at them I am not so sure vitons are really that necessary. At least in this case.
I did some fuel line taxidermy. I cut a injector return line in half and the line that goes to the pre-filter. I don't know how old the lines are. I imagine they are fairly new since they still look good, and aren't brittle. There was a little bit of cracking on the ends but nothing too bad. All the lines were still soft, no brittle lines. Here are the photos.

Fuel Line Taxidermy


Taxidermy Closeup


Injector Return Line


Pre-filter Line


Pre-filter Line End

__________________