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I understand that the JK takes regular gas (approximately 87 octane), but is it advantageous to put is higher octane levels (premium in the 90's? Thought higer octane would be better for performance and engine. Got conflicting information that higher octane is not good for the engine - confused?? Any thoughts out there?
 

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on a tv show they said it will only give you an advantage if your engine is knocky. they said that the fuel is thinner or something and for some engines it makes it work harder than it needs to to produce the same thing.
even if there was a perf. gain i dont think the 20 extra cents a gallon that is gone after about 220 miles is int worth it:D
 

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If after reading that article and you still feel the need for running higher octane then you would want to buy a tuner that will reprogram your engine parameters to run it.Of course,that same tuner will reprogram your computer to get optimum power from your 3.8 using regular 87 octane.:smokin:
 

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I ran a tank of 91 once for a road trip to CA...about 200 miles into the trip, check engine light went on.
I ran the rest of the trip, filled up with 87, and within 100 miles the light went off.

Never seen the light before or after.

Just sayin'...
 

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higher octane fuel burns slower so it is less likely to have pre-ignition or when the fuel ignites before the piston is at the top of the compression stroke. they are right you would need a tuner to take advantage of it.
 

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If you have a tuner and want maximum gains, go for it. Otherwise it's a waste of money, it will not make more power on its own.

However, I've never seen it cause a problem like a CEL, maybe on newer stuff.
 

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Just did an 800km highway trip in my JK with 91 Octane using the Superchips tuner and 91 octane tune.

Averaged 21mpg (US) one way (against a light wind) and 23mpg on the return trip (light wind at my back). Cruised at about 70mph (6th gear) for the majority of the trip. Dropping to 5th gear still required for the hills.

The 91 tune/fuel definitely improved highway performance (stock JK tire/suspension) over the stock JK and 87 octane.

Next trip I will be trying the 87 tune and 87 fuel.

I don't know how true it is, but the 91 Octane fuel at the Shell stations here are supposedly "Nitrogen Enriched" and provide extra cleaning over the 87/89 octane fuels....how true that is may just be marketing BS. Figured it couldn't hurt.

Grant
 

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I dunno about you guys but the manual says to use 87 octane...around here regular is 85 octane which means I use mid grade 88 octane.
 
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