Here in Iowa I can run 87 octane or 89 with 10% ethanol. The 89 is cheaper at the pump. I can also purchase 91 octane but I know that's a waste without a tune to utilize it.
Which should I run in my 07 5.4?

 

Whatever is cheap. No point in spending money on premium grades unless you have a forced injection or a tune requiring it.

 

Price may not be the whole story. e-85 is "cheaper" but for me there needs to be about .50/ gallon cheaper to overcome the loss in MPG to brake even.

 

Yes, i fully understand that. My biggest question is whether or not the ethanol is good for my truck.

 

Good for? Not totally sure. Harmful I don't think so, assuming you have a Flex Fuel vehicle. I am running a little test to figure out for sure where the brake even point is with my driving style. I get about an extra day without fueling with E-10, but it costs more. If all things are equal then I would rather just buy E-10 and fill less. They say to change the oil al little more frequent with the E-85 so perhaps some of the chemical reaction may cause some unwanted containments. I am not totally convinced either way.

I'll have mileage and cost per mile figures in a couple weeks.

 

My truck is NOT flex fuel. My buddy swears ethanol is bad for our trucks. I'm basically just trying to confirm he doesn't know what he's talking about.

 

Well that being said I would have to say that E-85 would be bad for your trucck, I would also say that E-10 is not bad for your truck. (07) perhaps a 82 would have issues because of the materials used back then were not rated to be used with E-10? not really sure there was a lot of Rumor back then about E-anything. I am not really sure what was ever proven.

 

In a car or truck that run's everyday 10% or more isn't bad. An outboard motor, atv or anything else that may sit for awhile and not run you may have problems. A fuel stabilizer is usually a good idea to add to the fuel. I run 87 with up to 10% ethanol with no problems.

 

I have also heard that adding any ethanol to gasoline for a truck that is not flexfuel can cause a little bit more wear and tear on the engine. Something about the heat of the explosion within the chamber. But I doubt it really does much, or else why would the govt. mandate it for all gas stations county wide. Well, don't answer that question; we already know that the govt. always acts in our best interest all the time no matter what.

I've heard that the wear and tear would probably be a difference of a few hundred miles on an engine's life span. But what about all those people who like to floor it and accelorate like a MFer. That's a lot of heat in the engine.

I got a question for anyone: does adding 10% ethanol to an 87 gas bring the 87 down to an 86 or 85? I would guess that it does, so does that mean that 89 is the new 87? I never thought about searching for an answer to this. I definitely see the MPG difference since the good ol' federal govt. mandated ethanol blending.

 

E-10 won't hurt you. I'd say nearly 90% of gasoline has at least some ethanol in it. If you aren't flex-fuel, stay away from E-85.

This isn't entirely true. I wouldn't use anything with more than E-10. Congress was pushing for E-15, but Automakers don't know that engines can handle it. 4 Cycle engines are fine... 2 cycle would be a concern.

Where did you hear that? I doubt there is any significant increase in wear.

Source? Ethanol has a higher octane rating than gasoline. Most drag cars run off methanol which is another alcohol like Ethanol.

No. Ethanol has over 100 octane rating. MPG has nothing to do with Octane. MPG has to do with energy density (Ethanol is less energy dense than gasoline).