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MOPAR Top Eliminator, Carlisle 2016
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It won't hurt, but you won't get any additional benefit from it either.
 

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2016 Challenger Scat Pack Shaker
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Less chance of knock on real hot days, that is about it.
 

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Senior Member
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It will never hurt, I've run 93 in mine since day one.
 

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Mopartial to Challengers
2013 Dodge Challenger R/T Classic
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I've filled my tank with 89 up until a few weeks ago. For the last three fill-ups I've used 91 (highest available in San Diego). What I have noticed is that my MPG average dropped from 17.5 to 14. I'm not completely sure the higher octane resulted in the MPG drop, in fact it doesn't make sense to me. But for my next fill up I'm switching back to 89 just to see what happens.
 

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Waiting for beautiful fall colors!
2020 Go Mango Scat Pack
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28,421 Posts
That is really interesting John. I use 91 as that is the recommended octane in the owners' manual. I only use pure gas, so my mileage is pretty good. I got 27 mpg to Rapid City & back. Even when I am in town a lot, it only drops down to 22 to 25 mpg.
 

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2016 Challenger Scat Pack Shaker
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That is really interesting John. I use 91 as that is the recommended octane in the owners' manual. I only use pure gas, so my mileage is pretty good. I got 27 mpg to Rapid City & back. Even when I am in town a lot, it only drops down to 22 to 25 mpg.
That is interesting it used to be 89 for the auto and 91 for the 6speed.
 

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2016 Challenger Scat Pack Shaker
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I run 87 in my R/T automatic which 87-89 is what the book says for an automatic and it calls for 91 with the stick shift, mine runs great and I get over 20 mpg even with this crappy summer blend and my engine does not knock at all.
 

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380 Posts
will it hurt if I run 93 octane in my automatic R/T
From The Owners Manual:

5.7L Engine (with Automatic Transmission)
The 3.6L and 5.7L engine (with automatic
transmission) is designed to meet all emissions
regulations and provide satisfactory
fuel economy and performance when using
high-quality unleaded gasoline having
an octane range of 87 to 89. The manufacturer recommends
the use of 89 octane for optimum performance.
The use of premium gasoline is not recommended, as it
will not provide any benefit over regular gasoline in
these engines.
 

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Packin up my game gonna head out west....
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2,470 Posts
That is really interesting John. I use 91 as that is the recommended octane in the owners' manual. I only use pure gas, so my mileage is pretty good. I got 27 mpg to Rapid City & back. Even when I am in town a lot, it only drops down to 22 to 25 mpg.
Sounds about where I was at pulling 27 mpg on the highway to and from MA to Carlisle. My work commute is a mix of city and highway and I'm getting around 22 mpg on those fill ups using 92 and 93 octane depending if I gas up at home or work.

Take it easy
Jay
 

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Slower Traffic Keep Right
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5,416 Posts
I am running a custom tune so I run 93 all the time, I have been going back and forth between 100% gas and the 10% ethanol stuff... not sure if it makes a difference yet...
 

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I have run 93 in my baby since day one, I just assumed that a higher octane gasoline would be better for my vehicle. I dont think I would ever use a lower grade, but thats just me
 

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801 RWHP
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^X2. Its a must with the tune now anyway. Well, if you don't want knock, that is.
 

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When I had an R/T I generally ran 93 fuel but also usually ran a diablo 91 tune. I don't have much confidence that most pump gas achieves the octane rating on the pump, so I figure to be on the safe side I usually go a bit higher than required.
 

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Premium Member
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9,085 Posts
Less chance of knock on real hot days, that is about it.
When I had an R/T I generally ran 93 fuel but also usually ran a diablo 91 tune. I don't have much confidence that most pump gas achieves the octane rating on the pump, so I figure to be on the safe side I usually go a bit higher than required.
This is my 2 cents also. Depending where you live and what type of driving you have to do....I could well see how on a 97 degree day stuck in bumper to bumper traffic running 87 in the auto might start recording knock that you would never hear but would start cutting back the fuel and timing. That and having no confidence in the true octane would be reason enough for me to use the 91 if I had an auto transmission. Another thing to consider is the past post I seem to remember where people running higher octane at the track where saying they consistantly had better times. Of course...none of the above matters if getting the very best horse power you can doesn't mean has much has saving the few cents per gallon at the pump has the car WILL run just fine without hurting anything under the worst conditions with the recommended octane if you are not worried about lossing some horsepower.
 

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Premium Member
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I've used the recommended 89 octane for 5 years and my car runs like a top. I've noticed about a 1.5 mpg improvement around town since I put the new exhaust on at least according to the evic.
 

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2016 Challenger Scat Pack Shaker
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I've used the recommended 89 octane for 5 years and my car runs like a top. I've noticed about a 1.5 mpg improvement around town since I put the new exhaust on at least according to the evic.
If I had the auto I would probably run 89 until the temperatures got into the 90s.
 

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389 Posts
I've filled my tank with 89 up until a few weeks ago. For the last three fill-ups I've used 91 (highest available in San Diego). What I have noticed is that my MPG average dropped from 17.5 to 14. I'm not completely sure the higher octane resulted in the MPG drop, in fact it doesn't make sense to me. But for my next fill up I'm switching back to 89 just to see what happens.
John,
I have been using 91 since day one and average 14/15 mpg too. Maybe I should try the 89!
 
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