2008 Z4 3.0si (Hawaii gas question)
OK, at this one Aloha (Top Tier) gas station near my home, they sell:
--Regular 87 octane with 10% ethanol (supposedly).
--Premium 92 octane with 10% ethanol (supposedly).
--89 octane WITHOUT ethanol (for boats).
Since my car calls for 91 octane minimum to run to its potential and is sensitive to ethanol (and the fact that gas cost $$$$ here), I was thinking of filling up my Z4 with 1/2 a tank of the 92 (with ethanol) and 1/2 tank of the 89 (without ethanol) resulting in a mixture that SHOULD be 90.5 octane and about 5% ethanol by volume.
Or....I could go 2/3rds of a tank of 92 and 1/3 of 89 resulting in a mixture that should be about 91 octane and 7-8% ethanol by volume.
Or....I could just put the 92 with 10% ethanol in and spend more money overall per gallon.
What would you guys do? The inconvenience of using multiple pumps does NOT bother me that much, I have done it before with another car.
THANKS - LoveBandit