R7 is now useless long term against petrol with 10% ethanol content.
R9 is much better but still not ethanol proof.
Even at 5% expect problems especially if your vehicle sits for any length of time as the ethanol in the fuel separates and starts eating pipes.
Also, due to it's hygroscopic properties it absorbs water and then begins to rust your tank.
At least you can get suitable bio proof hose but it's very expensive.
I bought 1 metre or 8mm + 6 stainless clips - £40
....but it's guaranteed by the maker against degradation.
This is going to be a big problem for us dubbers and there will
be fires caused by this
There really ought to be a sticky warning people of this problem and what actions to take in order to prevent horror stories.