Two tanks of nuthin!

I went on a trip with the car last weekend, I had two partial tanks of gas (~10 gallons each).  Just 87 octane, not premium, no E85.  I think I detected some pre-detonation on acceleration onto the highway, hard to tell.


No CEL's on the last tank with ethanol, but I only got down to about 3/4 of a tank.  My next tank will be 4 gallons of E85 and the rest 87 octane gas, just to prove one way or the other that I get a CEL or not over about 25% ethanol, which is what I found during the winter.


I'm now running about 13% ethanol in my tank, car running great.  No issues at this time.  Almost 159k miles on the odometer.

Tank #15

Since we are in the summer months, you'd think that the ethanol content of E85 would be higher.  But I have not seen evidence of that, no CEL's.


I've decided to increase my ethanol content a bit, going with 4 gallons of E85 instead of 3.5.  In the winter, this gave me an occasional CEL, towards the end of the tank and which would clear itself.  We'll see.


Gallons E85: 4.000 @ $1.949/ gal


Gallons 87 octane: 8.821 @ 2.249 / gal


Ethanol content of tank: 27.2%


Octane of tank: 90.7


Savings per tank vs. premium at $2.749/ gal: $7.6105

Tank 14

Pricing of E85 has improved.  It is now 30 cents less than regular gas.


Gallons E85: 3.507 @ $1.979/gal


Gallons 87 Octane: 10.5 @ 2.279


Ethanol content of tank: 22.64%


Octane of tank: 89.74


Savings per tank over premium at 2.779: $8.06


Getting 30 cents off really increased the savings per tank.