Recommended vs. Acceptable Octane in Gen 4 5.7

[Jerry1984]

I use 87 but plan to run 89 when I tow. I ran a tank or 2 of 89 and didn't notice any difference in mpg or performance.

 

[jsteinm1]

I always run 91 octane, but purely because its the only fuel in my area that is ethanol free. If there was an 89 octane with zero ethanol Id run that.

Just curious, why do you avoid E10 gas?

 

[Andy578]

Just curious, why do you avoid E10 gas?

ethanol isn't really good for it and it actually gives worse mpg. it's not as bad on modern injected engines but it's still not good and for anything with a carb it's horrible

 

[Crianor]

Haven't seen much 89 around here, Calgary. Unless you have a tuner or forced induction, you won't see any difference between 87, 89, or 91. Some of the higher octane fuels also throw in their own secret cleaners and other gimmicks. i'll save the 5 bucks and by a couple coffees on the way to work.

 

[bart98stang]

My 1500 Big Horn is bone stock and since the manufacture recommends 89 then I put 89 in. Those engineers and scientists are a lot smarter than I am.