I really don't think you need Viton anything. You just need to replace your fuel hoses because they're +- 20 years old. Biodiesel and the new ULSD simply exploit the microcracks and age-based flaws already present in your old lines. Since new lines aren't compromised, you have no worries there whether they're Viton or other.
I have fuel leaks since the switch to ULSD. Am I going to pay a premium for replacement lines made from Viton? Nope. Not necessary. Will I lose sleep because I did not use Viton? Nope.

For those of you that think Viton is now absolutely necessary, where you gonna find a Viton cigar hose?

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