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  #25  
Old 04-05-2011, 02:07 PM
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Re: 87 or 89 octane

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Originally Posted by Technosavant View Post
No argument on the sound, but if you REALLY want good sound, a member here (I forget who) had a Borla exhaust put on, and posted a YouTube clip of it. Now THAT'S awesome sound (I just crank up the stereo, myself..).

I remember a Car & Driver article from a few years back where they did comparisons of fuel types in given models. IIRC, if a vehicle wanted premium fuel, the drop in power (they measured at the wheels on a dynometer) was somewhere in the 5% range, but that varied a bit. Some cars varied a lot. Some almost none. But 5% stands out as the general average.

Given the engine to engine variances, that 5% is likely not even noticeable to the driver. But still, my wife's Acura specifies premium, and I've never fed it anything but. I stick to the manual's recommendations wherever possible, and I figure if the 30 cents/gallon was going to break us, we'd have been better off not getting a luxury brand.
I did listen to that and it does sound good.

I would think that since the manual states 87 is fine for our Hemi, the difference would not be that great. I ran 89 the first few tanks but switched to see if there was a difference. There wasn't so I stuck with the 87.
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  #26  
Old 04-05-2011, 02:33 PM
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Re: 87 or 89 octane

There's another explanation for the ECU adjustment. Sometimes you just can't get higher octane fuel and the ECU allows you the lower octane fuel albeit at loss of power and so forth.

I well remember being in an extremely rural part of AZ with my BMW M5. There was no other gas station for miles - the one station that was open did not have anything except 87. So I put in enough regular fuel to get me another 100 miles - then when I got closer to "civilization" I filled up again with premium. Anyway, the M5's ECU did what it had to do to let me keep going - hooray for that!
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Old 04-05-2011, 04:14 PM
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Re: 87 or 89 octane

I have almost 6k miles on my overland hemi and use 87 with no issues.

If the manual didn't say I could use 87, I would go with 89 even if it didn't knock or anything. But as you know the manual says either is fine (I can't imagine they would give you an option if 87 would cause a problem - just as easy to say 89 only IMO).
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  #28  
Old 04-05-2011, 04:46 PM
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Re: 87 or 89 octane

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Originally Posted by boarderman23 View Post
I have almost 6k miles on my overland hemi and use 87 with no issues.

If the manual didn't say I could use 87, I would go with 89 even if it didn't knock or anything. But as you know the manual says either is fine (I can't imagine they would give you an option if 87 would cause a problem - just as easy to say 89 only IMO).
It says 89, but 87 is acceptable.....not either is fine. You do get some better performance with 89 but if that is not important or noticeable to you then use 87. I did use 87 for almost 6 years in my 2005 GC with V8 Hemi MDS without an issue BUT when I had recently changed to 89 I noticed a reasonable difference that I wish I had used 89 all along (stupid me I suppose)....only 89 is going into my new one though....I learned.
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  #29  
Old 04-05-2011, 05:17 PM
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Re: 87 or 89 octane

I changed to 87 in the last week to test it and have seen a loss in MPG from 89. My commute is very consistent, same route home and back with little city driving. With 89 I was getting 21-22 MPG and with 87 I am getting 17.8 to 18.2. Am planning on going back to 89.

For reference I'm in San Antonio, TX.
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  #30  
Old 04-05-2011, 06:36 PM
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Re: 87 or 89 octane

It just depends on the engine and year. Use what your manual recommends.
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  #31  
Old 04-06-2011, 07:51 AM
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Re: 87 or 89 octane

As I stated earlier, I get better gas mileage using 89, so it actually works out to be cheaper to use than 87 octane. I also feel a little more power using the 89.

It would be interesting to find out from the folks with the hemi's that are complaining about the shuddering problem as to what octane fuel they run, and if anyone has switched fuel in either direction and had less shuddering as a result. I noticed very slight shuddering when starting to accelerate from anywhere in the 35 to 55 mph range on 87 octane, but it was very slight, but I haven't had it at all on the 89 octane, but I don't know if mine is just a result of the torque converter breaking in like some dealers have told people to wait for. I may switch back to 87 octane for a tank or 2 to see if the shuddering comes back.
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  #32  
Old 04-06-2011, 02:27 PM
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Re: 87 or 89 octane

I used 87 octane in my 2008 Overland Hemi. no issues regarding performance, nor mileage. Use 87 octane in my 2011 Overland Hemi. no issues regarding performance, nor mileage. IMO, using 87 vs higher octane, normal throttle pressure applied, not frequent WOT, there is NO difference. Honestly, when I do apply WOT on the highway (i.e. to pass a semi, or someone who has no business being in the passing lane), the HEMI responses as designed, no hestiation, no hiccups, just a smooth accerlation, and that lovely HEMI sound. Again, IMO.
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  #33  
Old 07-27-2011, 12:21 AM
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Re: 87 or 89 octane

I live in Colorado and all I see is 85, 87, and 91 Octane. I have a 2011 Grand Cherokee with V8 engine. My manual recommends 89 Octane, but I can't find 89. Which octane should I use?
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  #34  
Old 07-27-2011, 02:37 AM
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Re: 87 or 89 octane

I ran 87 the first three weeks I owned my jeep...got 13.3 mpg. Read the manual and decided to try the 89 since it was recommended over the 87...my gas mileage jumped to 16.8 mpg and I definitely notice the power difference
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Old 07-27-2011, 06:44 AM
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Re: 87 or 89 octane

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Originally Posted by jp467 View Post
I will be filling my tank for the first time with the hemi tomorrow. I know they recommend 89 in the Hemi, but I was thinking do you think you are buying old stale gas with 89 because nobody buys it or not. It was just a thought I had.

Pretty lame to get expensive hemi model and get cheapo on gas. Use what it suggested by Jeep.
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  #36  
Old 07-27-2011, 08:06 AM
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Re: 87 or 89 octane

I've got the Pentastar engine. Manual says 87 octane. Has anyone gotten better MPG with 89 with this engine?
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