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grifology 05-08-2012 12:19 AM

i know this has been posted before, but i couldn't find it.... i know the manual calls for mid grade fuel for the 5.7 hemi, but does it really matter?? been running mid grade and every third tank run premium... any suggestions???? i feel the difference when i put the premium in... it feels a tad bit stronger but i may be wrong...

dkerr24 05-08-2012 08:43 AM

The only thing you may feel by burning 91 octane is your wallet being a tad bit lighter. I run 89 octane (10% ethanol) in my truck, and every once in a while a tank of 87 octane (100% gasoline). I can't tell any difference at all in performance, but my truck is completely stock.


Asur 05-08-2012 08:43 AM

Unless you have a programmer that will change the way your engine will use the Diff grade fuel, It wont change anything, if you put higher octane fuel in your truck, the engine will knock, the ecu will then change the engine timing so as not to knock (ping), basically putting it in a position that will be just like running mid grade fuel. Now if you have a programmer, then that's different. Most Vehicles are made to run on 82 octane fuel, but you will never see that at the pump, ecu adjusts your engine for the ultimate fuel burning. Your vehicle's recommended octane is noted in the owner's manual and again unless you have your truck chipped, or have a programmer, then you will only be putting more money out for the same amount of fuel, you might see a very minute difference, but by the time you calculate your cost and that difference, you will see it just not worth it. That being said, putting higher Octane fuel will not hurt your engine since the ECU will adapt the Burning of that fuel as per what the sensors are sending back to it till it hears no more knocking. High Octane fuels will normally be seen in 10 cyl engines and up, some 8 cyl that are setup as high performance will also, but you will see the fuel Octane specifications in the manual at that point. If you chip your truck, add high flow everything on it, you will see that the chip manufacture will suggest you now use a higher Octane Fuel to take advantage of the new program, but other than that, your just wasting your money.

tison1200 05-08-2012 08:59 AM

I mostly run 89 with 10% ethanol. I ran a tank of 87 NON ethanol awhile back and got 18.6mpg hand calculated on a 300 mile trip. running 70-80mph.

snrusnak 05-08-2012 09:03 AM

89 is recommended. Running higher than that on a stock engine(stock tuning) won't get you any benefits. Running 87 will probably give a very slight decrease in power and mpg, but it won't hurt anything.

65Arboc 05-08-2012 11:45 AM

I've run 87 in mine since new. 6000 mi with no problems and I get 13 in town and 19 on trips unless I play hot rod with it;)

Grubrunner 05-08-2012 05:47 PM

Ram recommends 89 octane.... but does NOT require it.

Running regular [87] grade fuel will not hurt anything and your engine will run just fine.... and your wallet will love you. It will NOT void your warranty either should any injection problems or the like arrise. Why? Because 89 octane fuel is not "required" but merely "recommended" by the manufacturer.

Truth is, there are very few vehicles on the market that actually 'require' a high octane grade fuel.

Also, there's next to no consistency from gasoline marked "premium" to another marked "regular" from one pump to another [one town/city to another] so always look for the; therefore, always look at the federally mandater yellow sticker as to the exact octane rating you're pumping.

Remi12 05-08-2012 07:02 PM

Why does the Manufacturer "recommend" 89 Octane over 87 Octane ?

ONOutdoorsman 05-08-2012 08:43 PM


Originally Posted by Asur (Post 794453)
... if you put higher octane fuel in your truck, the engine will knock, ...

Let's not get silly :doh:

DodgeRam2012 05-08-2012 08:50 PM

Im also curious why Dodge recommends 89. They must of done some testing or research to write that in the owners manual

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