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87 or 89 octane on my 09 SE

3845 Views 10 Replies 11 Participants Last post by  DGibson
This week I experimented 87 instead of the preferred 89(according to the owners manual)with no side effects whatsoever .No loss of power,pinging,valve tapping etc.Ive heard that Chrysler now says that 89 is not necessary w/the 3.5 anymore.Does anyone here know anything about this?.What do you guys say? Thanks
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bro I have not seen any difference in either MPG or performance using 87 vs 89
 

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car was faster and more responsive with hightest and aggresive driving, over the last 18 months it has nothing but oldman driving and cheap ethanol stuff, there is a noticible drop in performance.
 

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i would stick with what the book says....if you are doing it from a money stand point.....you are only saving less than a dollar or two per tank....its all in your mind that you are saving a whole lot of money by going to 87...if something happens and you mess something up which is unlikely but could happen then how much will that cost??????? my advice is stick to the book
 

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Here's a way to test. All in one day. Go to the dragstrip with a quarter tank or less of nothing but pure 87 octane. Make a few runs. Then dump in a couple gallons of high octane race fuel (or even a couple gallons of 93 will do, I guess, as long as the average octane rises above 89 and you drive the car around a bit to get it all mixed in evenly), and make more runs. See if there's much difference in the times and speeds.

Take care to keep everything as equal as possible for weight across all runs.

If the computer is pulling timing on pure 87, horsepower will drop and your MPH will be slower. Probably the times too.
 

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I have had my Challenger SE for just over two years and 24k miles on it. Once in a while I will put 89 octane in it when I have a bunch of fuel rewards from Giant Eagle. I have not detected any difference in the way the engine responds or fuel mileage.
 

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When the weather is cool, you can typically get away with 87 Oct w/o feeling any difference. When you feel a difference it will be when the weather has warmed up and/or during heatsoak conditions. You won't hear any pinging or detonation. The engine just dials back output to whatever can run smoothly with the given octane and the temperature conditions. That's what a modern engine does.

When that engine bay gets toasty and the ambient air is hot and stagnant, you may discover that any modern engine can drink from 91 oct and exhibit perky operation compared to running on the lower stuff that the manufacturer has recommended. It's entirely conditions-based, not because one octane number magically works under all conditions for a particular engine. The number just indicates what will be sufficient most of the time.
 

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I ran 89 octane in mine , but I also had a predator with the 89 tune installed, ran great for me and got good milage on the road too.
 
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