were only just getting ethanol here in australia now in our cheap end fuel(and we hate it!!!),we get good 98 premium everywhere(no eth),we have the lower end peasant fuel is 10%flat beer(ethanol)at 91,then unleaded like 95 ,then the top shelf 98,,my high compression holden 5 litre v8 sings on 98 (pre smog type ,has a pcv only),with 16 degrees initial and 38 total,vac pulls it to 42 with high vacuum cruising,the dissy has been curved,,the 500 with xl125 pistons runs best on 98,its got a boyer ignition and you cant fiddle with the curve.,i had to have the combustion chambers machined to lower the compression a little,i dread the day our octanes lower,we havent had lead for years(80s)which is good all round for things like exhausts,plugs,oil contamination and childrens lungs.