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Old 10-01-2010, 10:13 AM
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Hemi Owners - Gas Octane Question?

The manual says 87 is acceptable, but 89 is recommended.

The gas station I like to use only has 87 and 93, so I was just thinking of using 87 since the manual says it's fine.

What do you think/use for yours?
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Old 10-01-2010, 10:47 AM
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Re: Hemi Owners - Gas Octane Question?

If you use 87 you might hear some pinging and then your ECU will back the timing off a bit, robbing you of power. You'll get better gas mileage, though. However, pinging is the sound of pre-ignition, which may cause long term over-wear on the engine. I run 89.
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Old 10-01-2010, 11:34 AM
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Dealer said he filled it up with 87 the day I picked it up. Still no problems but I have been using 89 ever since. I have not seen any real mpg difference between that first tank and later ones either like some people claim.
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Old 10-01-2010, 05:31 PM
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Re: Hemi Owners - Gas Octane Question?

Thanks for the responses.

I filled it with 89 today...I'd assume the dealer put 87 in it...so I ran the first 250 miles on that (assuming that's what they put in).
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Old 10-01-2010, 07:51 PM
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Re: Hemi Owners - Gas Octane Question?

Because it's my first tank, I filled with 89 octane but I plan to use 87. Modern engines should adjust for octane and avoid pinging.
My previous Jeep of over 8 years had the 4.7L HO which recommends 91 octane but 87 octane can be used with reduced power. I used 87 octane with the rare trial of 91 and could not feel any difference and never experienced any problems.
Fuel requirements are either required or recommended.
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Old 10-02-2010, 10:55 AM
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Re: Hemi Owners - Gas Octane Question?

I would suggest trying to find some definitive answer to this via a number of mechanics or engineers. It seems to me that the 87 would be a compromise situation, and the CPU compensates by dialing back the timing. Could this, since it's not the optimum, affect the engine life in some manner?
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Old 10-02-2010, 12:31 PM
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Re: Hemi Owners - Gas Octane Question?

Interestingly when Porsche was asked what octanes are recommended in their engines, they answered, "our engines are designed to be used any where in the world". In otherwords, any octane availabe.
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Old 10-02-2010, 12:41 PM
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Re: Hemi Owners - Gas Octane Question?

i use 89 or 93. mostly 93. i hate ethanol. i wish i could get my hands on real 100% gasoline.
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Old 10-02-2010, 01:48 PM
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Re: Hemi Owners - Gas Octane Question?

Thanks for all the answers...I'll probably just start using 87 as the manual says it's fine. It's cheaper and I can go to the gas station I prefer (they have 87 and 93 only).
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Old 10-02-2010, 05:04 PM
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Re: Hemi Owners - Gas Octane Question?

Dub, you are not going to get any benefit to using 93.
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Old 10-02-2010, 05:23 PM
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Re: Hemi Owners - Gas Octane Question?

the 93 i use "claims" to clean engine parts better than the 89 they sell. thats the only reason i use 93 at that particular station, which is the one i go to most often. other than that, i'll use 89.
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Old 10-02-2010, 05:49 PM
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Re: Hemi Owners - Gas Octane Question?

Sounds like marketing 101. The cleansing agents are "usually" in all grades.
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