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Hey guys, I've read just about everywhere online that the RT auto is to be filled with 89 octane fuel. However, my owner's manual states that it is to be 91 octane, regardless of transmission...can anyone help me out here? Obviously the average person would probably just do what the book says but I know a lot of you guys know way more than me, and have great amounts of engine knowledge, so I'd like to get your two cents worth. Thanks!

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huh? my service manual that comes with the car says 89 is recommended but would also run on 87. I stick to 89 or 91/93
 

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Ooops, guess I need to read my manual. I've been using 87 for the year and a half that I've had it with no problems. Of course, it won't chirp the tires when it shifts into second like most others say theirs will.
 

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What year?

This from the 2014 Owner's Manual


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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Mine's a 2012. Maybe I'll switch to 89 for a few months and see if there is a difference in performance. That could be while it feels kinda sluggish at times.
 

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I had 87 for a few months and then i went to 91 when i got the diablo tune. Got a more performance feel.. But in reality runs with anything
 

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Discussion Starter #9
I always opt for quality fuels in my vehicles. My girlfriend was reading the manual to me as we were on the 500km drive from the dealership. I asked her if she had read it correctly because I was skeptical that it would require 91 octane. I guess I will stick with good old 89 then.

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As I side note, the pdf file of the owner's manual you have linked to is signifcantly different than the one supplied with the car. Despite one being physical and one being digital, I woulf assume that they would be identical...strange

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There's been confusion before and, frankly, I think it comes from the way the manual is written. Fuel is addressed in two separate places. Anyway, 89 is recommended for the auto R/T. I've used 87 in my Charger R/T before and it did work, but the PCM adjusts the timing accordingly and you end up with a sluggish car that sucks more gas because you're on it more to make it go, so to me it's neither economical nor fun. I'd use it in a pinch, though.
 
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I ran 93 in my RT...

they don't sell 91 in my area. I would never run 87 in any V8 hemi. In the long run your motor will be better off. It may last longer and need less repairs.
 

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89 is a suggestion, but 87 will work too. I highly suggest 89 or higher. I put 87 in one time (the day I got it) and my friend about flipped his lid. The higher grade the fuel is, the more life and performance you're going to get out of the engine. I've been told this numerous times from numerous sources, so I've always gone with 89. Spend the extra 10 cents a gallon and take care of your car.

Analogy: It's like when your wife says to bring home a bottle of wine for dinner. You don't buy the cheap stuff. You buy the stuff that costs a little more and tastes much better because you want to please your wife and make her happy.

MAKE THAT HEMI HAPPY! GIVE HER 89!
 

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Come on, fuel isn't neither tasty treat nor medicine for your car. Use the rating recommended by the manufacturer unless you get knock, then you can try higher. Otherwise it's just a waste of money - it's not like premium means better in the case of gas. I think it's just labeled that way because they know people will gladly overpay to take care of their car. Save Money and Stop Buying Premium Gas

I've listened to people saying that 91 (we get nothing higher here) would cut down on the Hemi tick so I've tried for a while and... it didn't. Going back to 89.
 
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Another member here posted about ethanol free gas: Ethanol-free gas stations in the U.S. and Canada

I've been using 91 pure gas since last fall, not for the octane rating, but because it's ethanol free.

My car pulls stronger, and gets on average 2 mpg better with better drivability overall IMO. Bone stock, no tune.

May want to check your area out for availability, and try a couple of tanks worth.
 
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Ethanol question

Another member here posted about ethanol free gas: Ethanol-free gas stations in the U.S. and Canada

I've been using 91 pure gas since last fall, not for the octane rating, but because it's ethanol free.

My car pulls stronger, and gets on average 2 mpg better with better drivability overall IMO. Bone stock, no tune.

May want to check your area out for availability, and try a couple of tanks worth.
Based on the above comment, does 91 and 93 in the US have ethanol (BAD STUFF) mixed in?
 

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Come on, fuel isn't neither tasty treat nor medicine for your car. Use the rating recommended by the manufacturer unless you get knock, then you can try higher. Otherwise it's just a waste of money - it's not like premium means better in the case of gas. I think it's just labeled that way because they know people will gladly overpay to take care of their car. Save Money and Stop Buying Premium Gas

I've listened to people saying that 91 (we get nothing higher here) would cut down on the Hemi tick so I've tried for a while and... it didn't. Going back to 89.
I have never heard anyone claim it would rid the tick, it has nothing to do with it from my experience.

Honestly its all dependent on the quality of the gas where you live. In DFW, even the recommended 89 octane causes Long Term Knock Retard.

The only real way to know what the best gas to run would be is to data log. With that being said, the only thing your going to hurt running 87 is your performance and possibly MPG.
 

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I have never heard anyone claim it would rid the tick, it has nothing to do with it from my experience. [...] With that being said, the only thing your going to hurt running 87 is your performance and possibly MPG.
Yeah, that was in a thread on the tick and a long shot, but it was probably placebo effect for that poster. Typically people claim that synthetic oil does the trick... and I've been using that from the get-go without results either. I suspect the thinking about gas was that it would quiet down the injectors, but octane has nothing to do with it.

On 87, yeah, the TCM adjusts what it has to and it's just a waste of a performance engine, with a car feeling heat-soaked, but I don't think it hurts either. We're conditioned to think that more expensive means better. Now ethanol-free, that's something I'd like to try if they ever get that in my state (fat chance)...

I think that it's more important to buy top tier quality, fresh gas, than to go with the higher octane just because.
 

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Yeah, that was in a thread on the tick and a long shot, but it was probably placebo effect for that poster. Typically people claim that synthetic oil does the trick... and I've been using that from the get-go without results either. I suspect the thinking about gas was that it would quiet down the injectors, but octane has nothing to do with it.

On 87, yeah, the TCM adjusts what it has to and it's just a waste of a performance engine, with a car feeling heat-soaked, but I don't think it hurts either. We're conditioned to think that more expensive means better. Now ethanol-free, that's something I'd like to try if they ever get that in my state (fat chance)...

I think that it's more important to buy top tier quality, fresh gas, than to go with the higher octane just because.
I do agree that the higher quality gas is the best route.

But with that said I have tested it on all 4 of the 09+ Dodge vehicles I have owned. In my area (DFW) if you run anything less than 93 octane you are going to get high amounts of knock and reduced MPG. Four different vehicles, all the same results.

Now if you live in high altitude, it supposedly reduces the need for octane so you may see 0 knock running 87 and you will not get any benefit of going higher, but I have not heard of one single instance of anyone getting 0 knock on 87.
 
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