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For those that don't understand octane ratings, the SRT is designed and the engine is Tuned for 91+ Octane. The octane rating is the fuel's ability to prevent knock. This means you will get the advertised 475 hp when using the proper Octane rating. When you try to save $2-$5 per fill up, it won't immediately blow your engine and can be ran for while but you will get the following issues:

1. Engine will Knock (fuel will pre-detonate) and engine timing will be pulled. You will no longer be getting the 475hp you Paid $60-72K for.
2. KNOCK destroys engines. No mater how many counts of knock you get. It prematurely wears pistons, rods and bearings specifically. Knock caused by improper fuel and a lean cylinder will grenade your engine. Why make your engine work harder?
3. Engine will run rougher during idle and through the entire rpm band.
4. Fuel will not burn entirely nor correctly. Can cause carbon buildup and loss of gas mileage.
5. You will eventually get a Check engine light if there is too much knock. You will take it to the dealer, They waste 8 hours inspecting everything to simply tell you to put in 91 Octane fuel. You either have to pay for nothing or waste a warranty claim and waste their time. No mechanic enjoys doing this.

If you don't want to run Premium octane don't buy a performance engine. Instead buy an R/T with a 5.7, or even a GT w/ 3.6 and use E85. SRT 392s are performance machines and should be maintained accordingly. These are not your regular Durango. There's a different maintenance schedule and when stuff breaks it will cost more to repair. And please don't do a disservice to the next owner of your leased or short term owned SRT and let them deal with the long term issues caused by your ownership.
 

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Actually my R/T did a little 'lite' knocking on 87 the one time I tried it & I immediately went back to 89.
Can't imagine why you'd risk running anything less than 91 with the 6.4L !
 

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I kinda cheat a little....

On long highway drives...like I normally do, I use the cheap gas. I'm not stomping on her, Im just letting the ACC do its thing...dont need high octane for that.

When I am home and doing the city driving, Its highest octane available, either 91 or 93.

Haven't had issues and still get great gas mileage.
 

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I went with 89 Not knowing that it requires 91 Min and the knocking is insane. The car felt like it was going burst on a cold start. I eventually complained to the dealer and they let me know that you need 91 Minimum. I previously though 91 is for high compression only but turns out the motor is mid compression and needs it too. Long story short, I would highly advise against.
 

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I went with 89 Not knowing that it requires 91 Min and the knocking is insane. The car felt like it was going burst on a cold start. I eventually complained to the dealer and they let me know that you need 91 Minimum. I previously though 91 is for high compression only but turns out the motor is mid compression and needs it too. Long story short, I would highly advise against.
That's almost the opposite of what happened to me. My salesman/dealer filled it up for us when we purchased and put 87 in it, I know because he followed us to the pump. I did a search when we got home and found that it was supposed to be 91 minimum. I had an Acura in the past that had a 91 or above sticker on the inside of the gas flap, not sure why Chrysler doesn't do the same.
 

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I went with 89 Not knowing that it requires 91 Min and the knocking is insane. The car felt like it was going burst on a cold start. I eventually complained to the dealer and they let me know that you need 91 Minimum. I previously though 91 is for high compression only but turns out the motor is mid compression and needs it too. Long story short, I would highly advise against.
These motors are 10.9:1 compression ratio... That definitely falls into the high compression ratio.
 

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Buys $70k car, tries to save $2 per fill up.
It's a bit more than that. $0.65 per gallon difference times 20+ gallons = $13+ per fillup, per week(ish). That's $52 a month and over $600 a year. I'm not disagreeing that if you can afford a $70k car, you shouldn't skimp on the fuel. Just saying it's all a matter of perspective.
 

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Yeah, that is what i was told. I haven't been keeping up my motors so i was shocked to find it is this high. Between Mid and High I'm not completely sure of so I am probably wrong in calling it mid instead of high but Definitely needs 91 Octane Min
 

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2002 DODGE Durango SXT, 4.7L V8 32 teeth... Nicknamed: GREEN MONSTER
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I’d trust the owners manual over the dealer.

Owners manual specifically says “The use of 91 or higher octane “Premium” gasoline is required for in this engine.”

If it ends up knocking, causing damage, they’ll deny your warranty claim because you didn’t use the right octane.



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@Skippy426 you hit the nail square on its' head. Manufacturers look for any reason to void warranties.
 

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2017 AWD durango GT 3.6
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The PCM knows the difference in octane. So running 87 octane is no problem.
True but on performance engines requiring 91 min and the heatwaves there will be a lot of ping/knock. The PCM will respond by pull timing (generally makes the engine run hotter) which means less performance and potentially a hit in MPG.
 

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If it ends up knocking, causing damage, they’ll deny your warranty claim because you didn’t use the right octane.
The old fear of the voided warranty, this is not true. If you seriously think your buying premium from every pump marked with that label you are sadly mistaken. I worked at a gas station in my teens and watched the drivers put gas in the tanks. There is no regulation ever see the pumps that have five different octanes. They also make higher profit on the higher octane. Having one of the tuners review the logs from my diablo custom tune they knew that I was buying crap gas from the logs that were sent in. If you really want to avoid bad gas don't go when they are filling the tank. There is typically an inch of condensation water at the bottom of the tank that gets stirred up when they fill the tank.
 

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The old fear of the voided warranty, this is not true. If you seriously think your buying premium from every pump marked with that label you are sadly mistaken. I worked at a gas station in my teens and watched the drivers put gas in the tanks. There is no regulation ever see the pumps that have five different octanes. They also make higher profit on the higher octane. Having one of the tuners review the logs from my diablo custom tune they knew that I was buying crap gas from the logs that were sent in. If you really want to avoid bad gas don't go when they are filling the tank. There is typically an inch of condensation water at the bottom of the tank that gets stirred up when they fill the tank.
My dad worked for Gulf oil years ago... he always said, if you pull into a gas station to get gas and there is a tanker filling the tanks at the same time, pass and find another station...
 
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Really - I don’t see any change in MPG at all 8991/93 get the same MPG ……
Depends on how you drive. With spirited driving in hot weather I noticed a difference between 87 and 91 on my 2013 JGC 5.7, not to mention 87 octane pulled more timing. If you have a means to log knock I recommend you try comparing the 2 fuels. However you should reset the adaptives before you do so.
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I'm sure there are some folks thinking ..why can't I just use octane boost to a tank of 87....discuss...
That comes up on the challenger forum once in a while. Not cost effective, plus the one sold in autoparts stores usually does not raise the octane up like torco or boostane. Also octane boosters use MMT which leaves an orangish-reddish residue that can start clogging up O2 sensors and spark plugs.
 
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