Ethanol or No Ethanol, That is the Question
Thread Starter
Super Member
Joined: Dec 2008
Posts: 554
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From: USA
2021 GLE450W4 SUV
Ethanol or No Ethanol, That is the Question
Around here there is 91 octane gasoline with up to 10% ethanol. There is also 90 octane without ethanol. That's about a 1% difference in octane.
Which is better? Does it matter?
Which is better? Does it matter?
MBWorld Fanatic!
Joined: May 2018
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From: Boise
2024 GMC Canyon Denali..... 2018 Audi SQ5
I would go with the Non Ethanol. My understanding is that Octane is determined at the Refinery...and is higher at low elevations than at Altitude for equivalent fuel. Apparently the higher Altitudes lower the final calculation-per a friend that owns a Chevron Station.
Super Member
Joined: Jan 2020
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From: Fredericksburg, VA
2020 Mercedes GLE350 4Matic; 2023 Tesla Model Y
Octane is the measure of how much compression a fuel can withstand before igniting. Or, in layman’s terms, the higher the octane rating, the less likely the fuel is going to pre-ignite (read: explode unexpectedly) at higher pressures and damage your engine. MB requires a min octane rating of 91 due to their high compression engines. Use the 91 octane, 10% ethanol fuel (B10) doesn’t have any impact on detonation pressures. If however, you have a choice of no ethanol, 91+Octane fuel buy it. Ethanol B10 fuel has less BTUs per gallon than no ethanol fuel, so more heat will be generated per gallon if the gas doesn't have any ethanol — in English that means you’ll get slightly better gas mileage/performance.
Last edited by TexAg91; Feb 4, 2021 at 07:11 PM.
