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Billyk24

Unleaded 88 coming your way?

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Stopped at the Kwik Trip station(s) in Rhinelander, Wi as I noticed the large sign advertising unleaded 88.   Stopped at the pump and found out unleaded 88 is E15.  Marketing move?  The Kwik Trip station near the Central Wisconsin airport (just south of Wausau) does not have unleaded 88.

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I like under E50 for vehicles. E30 would quickly become my favorite. All vehicles that I've experience do well under E50. My wife's Focus will drop 2 mpg on E30 E40 fuel. Given that the E85 fuel is -60 cent continuous spread I'm making out good. Funny, that the Costco pumps may be as much as -10 cents per gallon and you have to get in line with six deep to fuel up. If ever the public would realize the true benefit of ethanol, you know given that the fuel really is a superior fuel, what would be the results? And yes the regulations to improve production and use of ethanol should have merely allowed ethanol to mix straight up with gasoline and advertise as mid and high octane fuel.  

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I've been running E15 (Kum & Go) in my 09 Cobalt for over a year now, occasionally I'll top off a half tank with E85 for a E50 blend,  I loose about 3-4 mpg (8-10%) with E50, much over E50 I'll get a CEL.   

 

Off topic:

 

Got my wife a 15 Rogue last December, her previous 2 cars were FFV.  Got in it one Sunday morning, didn't start as quick as normal, after a few miles noticed a CEL, it was full so stopped to check the gas gap.   Few miles it didn't go away, asked where she filled it up.  Sure enough almost a full tank of E85.  After 50 miles, I squeezed in 3 gallons of E10, still didn't clear, brought the blend down to about E65, it got 24 mpg per the display on E85.  On E65 for the next 160 miles I got about 25 mpg per the display.  I topped it off with 6 gallons of  E15 bring it down to E45 and got 28.2 mpg when I got home 60 miles later.  I would normally expect 30-31 mpg for that trip. 

 

The next day the light was gone.  Other than not starting instantly the first time no other symptoms. 

 

I'd run E50 in all my cars and never give it a second thought if available. 

 

 

 

 

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The unleaded 88 price is now 10 cents a gallon less than E10 at this Northern Wisconsin location.   As for mpg, driving Mom's 08 Mercury Milan (V6 engine) is netting me around 32 driving on the state highways and interstate from the 50-62/63 mph range.  Yes, I drive a little slow.

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When should you buy E15?  Depends on your metric!  I try to go for miles per dollar, or cheapest GGE.  So how do you figure that out?

Assume that you'll get nothing out of the extra octane (though you might get better mileage from better timing/less anti-knock retardation), and just focus on the energy content.  We'll need to figure that out.

I like in Lake County, IN, which is just outside Chicago.  That's important because that means the gasoline is reformulated, so the energy content is slightly different. Wikipedia lists the energy content of a gallon of RFE10 at 111,836 BTU.  A gallon of pure ethanol, E100, is listed at 76330BTU/gallon on energy.gov.  So far, so good!  So how much would a gallon of E15 have?  Well, it's part E10 and part E100, let's find out how much of each.  E10 is 9 parts gasoline to 1 part ethanol.  E15 is 85% gasoline.  So the E10's amount's gasoline will be the 85% part and the remaining ethanol in the E10 will be 1/9 of that amount.  85*(10/9) makes 94 4/9 percent E10.  Add 5 5/9 percent E100 and that will make up all 100% of the E15 mixture.  111,836*.944444 + 76330*.055555 is 109,863BTU/gal.

Around here, E15 is usually 5 cents less a gallon than E10.  So at what prices per gallon is the energy content per dollar equal?  Or at what prices will your $20 of E15 have the same BTUs and propel you the same distance as your $20 of E10?

E15price*E15gallons=E10price*E10gallons
E15price = E10price - $0.05
109863*E15gallons =111836*E10gallons  or E15gallons = (111836/109863)*E10gallons
(E10price - $0.05)*(111836/109863)*E10gallons = E10price*E10gallons
A=(111836/109863)
(E10price - $0.05)*A = E10price
A*E10price - E10price = $0.05A
E10price(A-1) = $0.05A
A - 1 = 1973/109863
E10price = $0.05*(111836/109863)*(109863/1973)

E10price = $0.05*(111836/1973) = $2.834

Okay!  So at an E10 price of $2.834 a gallon, and an E15 price of $2.784 a gallon, you will get an equal amount of energy per dollar.  If the E10 price is lower than $2.834, you should buy E15 if the difference between the two is 5 cents (a very common spread around here).  That makes sense, since if E10 were $0.10 and E15 were $0.05, you'd get twice as many E15 gallons and energy than E10.

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From the last line:

E10price = $0.05*(111836/1973) = $2.834

It's the price difference and the energy difference that sets the break-even price.  If the price difference was 6 cents, it would be:

E10price = $0.06*(111836/1973) = $3.401

making E15 a better deal just about everywhere.  If it was 4 cents, it would be:

E10price = $0.04*(111836/1973) = $2.267

Which is hard to find anywhere these days.  It seems that E15 at a nickel less per gallon is priced exactly where it should be, to offer a (slightly) better deal on BTU/dollar, encouraging purchase and use.  It'd be a much better deal at 6 cents; you'd have to find a reason not to use E15 at that price spread!

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