70 percent of 113 blended octane ethanol combined with 30 percent of 85 octane gas. This "E70" blend is used in colder climates/at colder times to insure good starting and is the minimum ethanol content in E85. The octane should be higher when summer blend E85 is actually 85 percent ethanol. Also it is possible the gas used could be 87 octane in some cases.