I friend told me I have to buy "R9" fuel hose because it has a linining that is compatible with today's fuel at the pump. The over-the-counter hose at Advance is "R6" as stamped on the hose. My friend says the R6 linning will break down over time with today's pump gas. The guy at Advance didn't know what i was talking about.

Can anyone shed some light on this?

Your friend might be right, although I have no direct experience with this. Todays fuels have a small percentage of alcohol (ethanol) in them by government mandate. Alcohol reacts with different things than gasoline does, so I'd say it's possible that older-style rubber fuel lines could be susceptible to being broken down by that ethanol content over time.

I'm actually interested in hearing other's input on this. I got a lot of little bits of rubber fuel line here and there on my cars!

The guy at Advance didn't know what you were talking about? Wow, shocking. ;) Stick around the board a while. There's quite a few guys here that know maybe just a little more than the local parts monkey across the parts counter.