I have a new 2012 Durango crew v6 awd flex fuel. I'm wondering if the engine can take adventage of 91 octane E0 and if the lack of ethanol in the fuel would improve performance and fuel economy. Thanks.

 

Your truck is not likely to take advantage of the increased octane and also the flex fuel is not likely to pay off since you have a decrease in MPG when using that. Your best bet is to just stick to the manufacturers recommendation for unleaded fuel.

 

Your truck is not likely to take advantage of the increased octane and also the flex fuel is not likely to pay off since you have a decrease in MPG when using that. Your best bet is to just stick to the manufacturers recommendation for unleaded fuel.

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Thanks for the reply rdkind. I guess my question is really to distinct ones.The E0 however is not flex fuel but just fuel that is not diluted with alcohol. The alcohol has a higher octane than gasoline (circa 108 versus 87-93) but about 67% the energy by volume. So if the engine can adjust timing to burn E85 with a higher octane (i.e. resistance to spontaneous combustion under pressure) then can it adjust to use the 91 octane?

Secondly will gasoline @91 octane E0 give better gas mileage and performance. 87 E10 is the standard fuel here in Missouri but the added ethanol reduces the energy of the fuel by about 4% although folks who use E0 tend to report mileage gains of around 8-10%. Unfortunately here in MO the only grade that is sold as E0 is 91 octane.

I guess a third question is can the 91 octane damage engine components such as a catalytic converter?

 

while towing a 22ft enclosed trailer to Montana and back I noticed I averaged around 11.00 mpg with 91 or higher octane fuel

I got stuck once putting in a half tank of 87 and gas mileage went down to 8.8

big difference!

 

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You're R/T has the 5.7 Hemi though doesn't it? Results could be different for the V6. Right now I have a tank of 75% Shell 87 E10 and 25% Unbranded 91E0 and am getting between 18-19 mpg 80% (hilly) city with under 500 miles on the engine. Seems pretty good to me. I want to make sure 50-75% 91 E0 won't do any harm to the engine. I may just have to experiment to see if the 91 E0 delivers desired results.

 

test it out while its under warranty and let us know...lol

 

was hoping someone else had done that for me!

 

If it is unleaded, then your catalytic converter is safe.

EO should always deliver better MPG than E10 (and has every time I tested it).

As mentioned - -> gasoline has more energy than ethanol.

 

And the reason ethanol has the higher octane is to allow it to burn. Higher the octane, the slower the burn.

 

I would get the E0 even if it's higher octane then is required. I live in a county where E10 is the law so when ever I go on road trips I notice my mileage go way up, one, because of HWY driving, and two, because E0 gas.

The owners manual indicates the recomended octane but doesn't specifically say don't use any higher grades. For me, I've been blending 50/50 of 87 & 93 because that's what they sell at Costco and for the Hemi Dodge recomends 89 octane.