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-   -   87 vs 89 octane for hemi v8 5.7 (http://www.jeepgarage.org/f73/87-vs-89-octane-for-hemi-v8-5-7-a-52559.html)

mikeh1955 01-07-2013 09:20 AM

87 vs 89 octane for hemi v8 5.7
 
I have a 2013 v8 5.7 hemi and don't get MPG advertised in either city or highway. City around 11-12 and one trip I made so far on highway was around 18-19 setting cruise at 70. I'm from western Pa and most cars do not get advertised mpg due to hills and winding roads
My question is, has anyone checked mileage using 87 octane vs 89 in the v8? The manual reccommends 89 but says you can use 87. I've been using 87 but am going to try 89 to see if it makes a difference. No mention was made by the dealer about using 89 when I bought it. Found out when I finally read the owners manual...lol

BuckeyeSRT 01-07-2013 09:31 AM

Re: 87 vs 89 octane for hemi v8 5.7
 
Lots of discussions about octane here.

Jim_in_PA 01-07-2013 10:01 AM

Re: 87 vs 89 octane for hemi v8 5.7
 
As Buckeye indicated, there have been many threads about this.

That said, I run 87 exclusively and get 20-22 highway and average just under 16 in regular local rural driving. (not super hilly)

JeeperJohn 01-07-2013 10:06 AM

Re: 87 vs 89 octane for hemi v8 5.7
 
Yep, this subject is like an oil thread or tire thread. I've used both 87 and 89 for periods of time and have detected absolutely no difference in either performance or mileage.

comnjeep 01-08-2013 10:37 PM

Re: 87 vs 89 octane for hemi v8 5.7
 
And everyone overstates their mileage...

77rednecktruck 01-09-2013 07:48 AM

Re: 87 vs 89 octane for hemi v8 5.7
 
Quote:

Originally Posted by mikeh1955 (Post 733700)
I have a 2013 v8 5.7 hemi and don't get MPG advertised in either city or highway. City around 11-12 and one trip I made so far on highway was around 18-19 setting cruise at 70. I'm from western Pa and most cars do not get advertised mpg due to hills and winding roads
My question is, has anyone checked mileage using 87 octane vs 89 in the v8? The manual reccommends 89 but says you can use 87. I've been using 87 but am going to try 89 to see if it makes a difference. No mention was made by the dealer about using 89 when I bought it. Found out when I finally read the owners manual...lol

i am in Pittsburgh and get 11.5 in the city regardless of octane. I do get over 20 on the highway fully loaded with luggage for a week with 3 kids though. I normally set the cruise on 73 when on the highway.

bill_de 01-09-2013 08:09 AM

Re: 87 vs 89 octane for hemi v8 5.7
 
Quote:

Originally Posted by comnjeep (Post 735016)
And everyone overstates their mileage...

And most everyone drives more aggressively than best gas mileage would dictate. In any event, these mileage numbers were never intended to tell you what kind of mileage you will get, but just to compare one vehicle to another. Maybe they should just convert the results to a score of 1 - 10 so folks don't set their expectations to high.

From a window sticker;

"Actual results will vary for many reasons, including driving conditions and how you drive and maintain
your vehicle. The average new vehicle gets 23 MPG and costs $11,600 to fuel over 5 years. Cost
estimates are based on 15,000 miles per year at $3.55 per gallon. MPGe is miles per gasoline gallon
equivalent. Vehicle emissions are a significant cause of climate change and smog.
Actual results will vary for many reasons, including driving conditions and how you drive and maintain
your vehicle. The average new vehicle gets 23 MPG and costs $11,600 to fuel over 5 years. Cost
estimates are based on 15,000 miles per year at $3.55 per gallon. MPGe is miles per gasoline gallon
equivalent. Vehicle emissions are a significant cause of climate change and smog."

Jim_in_PA 01-09-2013 03:37 PM

Re: 87 vs 89 octane for hemi v8 5.7
 
Quote:

Originally Posted by comnjeep (Post 735016)
And everyone overstates their mileage...

I didn't...I calculate manually.

Truck11 01-09-2013 04:50 PM

Re: 87 vs 89 octane for hemi v8 5.7
 
We have been using 87 for the last year - 11 or 12 around town - 18-19 maybe 20 highway.
Now it idles rough and the 'official' response from the dealer was... "could not find issue with idle, try using 93 octane for 1500miles to see if that clears it up, these Jeeps prefer 93" WTF?

ColdCase 01-09-2013 08:05 PM

Re: 87 vs 89 octane for hemi v8 5.7
 
I found that stale gas or high ethanol content has more of an adverse affect on mpg and performance than simply octane. When you change fuel. it takes maybe a half tank for the computer to adjust.

I have a 2011 V8 Overland. With good 89 octane fuel I routinely see 23mpg highways on the ~600 mile trip from Pittsburgh to Boston (ACC set at 75). I saw a high of 25 on one occasion. The motor runs smooth, no vibration even in ECO mode. With good 87 octane I see 22 mpg but there is some roughness and lack of snap. Poorer quality fuel will drop that mileage down to 19-20 and also degrade smoothness and snap.

As others will say, your mileage may differ. There are enough production variances to explain a wide gamut of experience.

five.7 Hemi 01-10-2013 12:54 PM

Re: 87 vs 89 octane for hemi v8 5.7
 
Man, I have never seen 11-12 mpg in the city and I drive it pretty hard. The lowest I have seen was 13.8. But this is in Houston @ sea level and flat roads.

oh and it's a 4x2, I also run 89 all the time.

comnjeep 01-13-2013 01:45 AM

Re: 87 vs 89 octane for hemi v8 5.7
 
Ive never noticed a difference from 10%etoh in any respect frankly, neither do the writers at grassroots.

89 is recommended and so little more $ than 87 why not use it? Mileage may not matter but low oct could cause knock then timing gets pulled then less power and performance.

Jeep figured it out so u dont have to, theyd never rec a higher grade than needed, why would they?


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