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Can you mix E85 and gas

exhummer guy

Full Member
Joined
Mar 8, 2008
Messages
13
Location
wisconsin
dealer was nice enough to fill my 07 up with fuel when I picked it up now down to half tank can I fill up with E85?? anything i should worry about ? My first flex fuel vehicle
 
You can. The engine management computer will adjust to any blend up to 85%. However, you might want to run a few tanks of regular gas through it first to establish a baseline on your average fuel economy.

When you switch to E85, be prepared for a BIG drop in fuel economy. Many see a drop of 30% to 35% from gas to E85.

Ya gotta pay to be green.
 
will do and thanks for the info, and with E85 running about .85 lower than gas I think it will be a win win for me
 
Ive been running 70% e85 and 30% regular gas because of the cold weather out here in Colorado. It seems to be working out fine. I go 100% e85 in the summer though.
 
Aussie Red said:
yes you can and it runs fine. Hard to always find E85 .

Or in my case...impossible.  There are only 5 stations listed in Georgia and none within 150 miles of me.  So fossil fuel it is...
 
I think GM recommends burning at least 7 gallons of the existing fuel in the tank prior to switching to the other.  That shouldn't be a big deal in the AV - just accelerate hard from a stoplight and watch the needle drop!  :D
 
My dealer said to make sure it was below 1/4 tank before switching to gas or e85.

:rolleyes:

Maybe he was wrong?
 
I think I remember a "break-in" period recommendation using fossil gas, but there is no reason that you can't use 100% E-85 or any percentage below.  The computer will adjust to any percentage.  I use both fossil and E-85 and re-fill at all ranges of the gas guage.
 
pj41 said:
My dealer said to make sure it was below 1/4 tank before switching to gas or e85.

:rolleyes:

Maybe he was wrong?

He was wrong, although I tend to do that anyway.
 
Rocky07 said:
Yep. dealer was wrong (not unusual).  Mix it how ever you want.

Interestingly, the dealer may have a point here - my prior post had GMs recommendation (use at least 7 gallons), but I have been alternating between E85 and Unleaded lately, and I have found that if I dont burn the E85 tank down to almost nothing, the mileage remains at an E85 level (when I full up with unleaded and some E85 is remaining in the tank).  I have a feeling that the computer errs on the conservative side when a mixed fuel is in the tank, and injects more into the cylinders as it would with full E85.

I would be interested in others experiences with this - now that I am back to full unleaded, I am averaging 17-18mpg.  I will continue to use E85 when it is available at the right price, however!
 
I'd been sorta thinking the same thing. It takes a tank or two for my fuel mileage to stabilize when switching and the "in between" mileage is lower. I don't randomly mix and match fuel types and never refuel above 1/4 tank, fwiw.
 
My company vehicle is an 07 Impala Flex Fuel. We have E-85 at work and I try to use it as much as possible, but sometimes I have to use regular unleaded and mix it with the E-85 in the tank. I have not experienced the condition that ss1 mentioned in a previous post. If I use only E-85 I get about 20 miles to a gallon city & Highway mixed driving. If I use only regular unleaded I get about 25 miles to a gallon. When I mix the two fuels I get anywhere in between the 20 & 25 MPGs depending on how much of each fuel I have in the tank. The more E-85 the MPG's stay in the 20 to 23 MPG range. The more regular unleaded the Mpg's stay in the 23 to 25 range.
Maybe the Impala has a better ethanol sensor than the AV  ???
 
Are using the onboard computer to calc mileage or the pencil at the pump method (which if you keep good notes is 100% accurate, the computer is not).

E85 is "mixed" to begin with (its 85% ethanol and 15% gasoline).  Your vehicle can run on any "mix" of gasoline and ethanol up to 85% (ethanol).  "Regular" winter blend gasoline is E10 (10% ethanol) and is safe for all cars (hard to believe I know).

Ethanol is not the devil. 
 
When ethanol first came out it was E10 or E15 and many people wouldn't use it, it was usually labeled economy. Most stations still sold regular/midgrade/premium with no ethanol, unless premium is required older vehicles can burn E10 no problem.

My DIC is accurate highway, I can't use E85 in my '04. The computer will adjust to burn anything from E10 to E85, only way to compare accurately is by pencil over the same route, same driving habits, same driving conditions. No surprise there.

The V8 engne was first with flex fuel and then they added the variable displacement option. I'd expect as they add the flex fuel technology across the engine line the computers will tune them to operate at increased effiency. Right now they are still adding it
 
I guess I am going to have to test how the mileage is on my trip to Wild west. I have never noticed any difference really but then I rarely use the AV. I don't drive much because I no longer go out and punch a time card  :laugh:
 
Flint4x4 said:
When ethanol first came out it was E10 or E15 and many people wouldn't use it, it was usually labeled economy. Most stations still sold regular/midgrade/premium with no ethanol, unless premium is required older vehicles can burn E10 no problem.

My DIC is accurate highway, I can't use E85 in my '04. The computer will adjust to burn anything from E10 to E85, only way to compare accurately is by pencil over the same route, same driving habits, same driving conditions. No surprise there.

The V8 engne was first with flex fuel and then they added the variable displacement option. I'd expect as they add the flex fuel technology across the engine line the computers will tune them to operate at increased effiency. Right now they are still adding it
I think I remember that ethanol was used to replace the highly toxic MTBE.  When I first moved to Denver the gas was oxygenated with ethanol between November and February but now it's all year.  The Shell products here say "up to 10% ethanol may be used..." on all 3 grades.  I run the low grade in the Av and the premium grade in another car - no problems.
 
jeffbco said:
I think I remember that ethanol was used to replace the highly toxic MTBE.

Yes, but originally it was used for economy grade gasoline. MTBE was used to replace lead, we had leaded/no lead for years. I'm unsure exact formulae used but they found a way to use ethanol/E-10 and ditch both MTBE and lead.
 
Flint4x4 said:
Yes, but originally it was used for economy grade gasoline. MTBE was used to replace lead, we had leaded/no lead for years. I'm unsure exact formulae used but they found a way to use ethanol/E-10 and ditch both MTBE and lead.
Lead?

I remember 1989/90 having a 65 Chevy P/U that ran "regular" (lead) gas still (I was too cheap to pay for the engine upgrade to run unleaded).  I was in Colorado and lead gas was everywhere.  I took a trip to the east coast and quickly discovered that no one sold lead anywhere east of the Mississippi. (And that was almost 20 years ago).

JP
 
SabreXray,

I remember some people using a fuel additive or at least premium no-lead to prevent knocking. Regular (leaded) was cheaper but would trash your catalytic converter, many people gouged thier fuel fill neck so the (regular) nozzle would fit. I had cars that burned regular (leaded) and I'd put whatever gasoline was cheapest in them, I didn't care if it was no-lead or contained ethanol. I think many of the early economy flavors were 15% alcohol around here.

I'm curious what mileage I'd get with E85 on my non flex-fuel '04 ? I'm not going to test it because I know my fuel system isn't capable of handling the corrosive quality of that much alcohol. I'm sure it would burn without much problem, likely get really lousy mpg too.
 
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