Reminds me of when I dissected earthworms in high school biology. I once thought that one needed Viton to run B100, but have since rescinded that opinion. I assume now that it's just 20 year old fuel lines that need replacing with new, Viton or otherwise, that are required. I can't see how bio would cause microcracks like that, that would imply that bio dries the rubber out like gasoline would and I just don't think that's true. Those cracks are due to age and or heat, and that's what causes the leaks. I'm also assuming you weren't leaking and just replaced your hoses as a matter of course.

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'02 BMW 325i
'85 300D 450k
'93 190E 2.6 170k(killed by tree)
'08 Ducati Hypermotard 1100S 6k
'06 Ducati S2R800 14k(sold)