The bright green/yellowish Tygon (F-4040-A) holds up to ALL fuels, way better than stock fuel lines.
It hasn't hardened, discolored,
****, stretched out around fittings, or gummed up in the 10+ years I've been buying it.
Use it for avgas, pump gas, oil, brake fluid, hydraulic fluid, ATV, etc. without any problems.
Stock fuel lines don't last long in desert conditions, they harden up to the point you could probably use them for drill bits.
Haven't had any luck with Tygon clear tubing, or any clear tubing for that matter.
Tygon is a brand name, so just because it's Tygon doesn't mean it's the right composition.
Get the Tygon F-4040-A:
http://www.usplastic.com/catalog/item.aspx?itemid=23487