85 octane regular gas mid west states?

In the Black Hills area of South Dakota, most gas stations have 85, 87, and 91 octane fuel. Their REGULAR grade 85 octane fuel does NOT contain ethanol so it costs more :? then their PLUS grade 87 octane fuel which contains 10% ethanol. The PREMIUM grade 91 octane fuel also contains 10% ethanol.

The owner's manual for my 2014 F150 Ecoboost engine says to use 87 octane or above at all time, including in the mountain areas that may have as low as 85 octane.

My owner's manual also says 87 octane is good for my Ecoboost, but further says that premium 92+ octane is probably best for the engine, when pulling a trailer, and especially when in the mountains.

time2roll wrote:
Probably fine with 85... however I use the next higher grade as my owner's manual says 87 minimum.

Yep, as do I.

In our travels, I see a lot of 85 octane gas at the pumps but have never seen where a higher octane wasn't also available. I never use gas with less octane than the owner's manual calls out.

Thanks to all for your replies. I really appreciate it.

Fishy

Keep in mind that turbo charged engines have nearly the same octane needs regardless of elevation.

IN the mid-west (IE: Michigan) 87 is no tribble at all

IN THE MOUNTAINS I've seen 85.. Seems at higher altitude you don't need as much Octane (Actually I understand why that is but I'd rather not get into a technical post just now)

But I recommend avoiding it less you plan on STAYING at high altitude .. Go Mid Grade if you encounter it.

DougE wrote:
Your computer-controlled car can compensate by reducing timing advance if necessary.

That's spark knock.

If it is so bad that you are getting true compression knock, then playing with the timing won't help any......since the fuel ignites BEFORE the spark hits.

Thankfully that condition is pretty rare.

MEXICOWANDERER wrote:
85? News to me :(
More alcohol?

No. E100 has an "octane" rating of about 100.

You just missed all of those previous discussions about this.....that have been going on since about 1930 or so. ;)

Lower octane fuel is cheaper to make.

The lower variety works just fine at higher altitudes.

Your computer-controlled car can compensate by reducing timing advance if necessary. Best to fill up often so you don't get a full tank of it though.

I follow the Chevy owner's manual recommendation - "Do not use gasoline with an octane rating below 87, as it may cause engine damage and will lower fuel economy."