I'm afraid your notes are wrong Dennis - link to SAE specification here
Essentially R6 is okay for carbs and over 5% ethanol, R9 is rated for higher pressure of injection systems and R10 is for systems where the hose is immersed in fuel (inc bio/ethanol)[/quote]
That was part of my read up.
I think you may have misread those specs....the last bit of the R6
"Exposure of these hoses to gasoline or diesel fuel which contain high levels, greater than 5% by volume, of oxygenates, i.e., ethanol, methanol, or MTBE (methyl tertiary butyl ether), may result in significantly higher permeation rates
than those listed for 30R6, 7, or 8."
I take that to mean that you would get higher permeation rates than the rates listed for R6 with ordinary petrol.
The pressure part of the spec is of course of no interest to our low pressure systems.
Anyway at under £5 per meter for R9, the cost of renewing just under 2 meters is not too horrendous.