Octane used on a 2012 PW

the manual says to use 89 but my employee pays for all my gas so should i should 91 instead or is the truck programed to perform best with 89

89 octane is recommended.
87 is ok.
91 is of no benefit.

walc said:

89 octane is recommended.
87 is ok.
91 is of no benefit.

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gotcha thanks

I am aware that this is an old post, but at high altitude locations in Colorado, Wyoming, Montana, New Mexico, Utah, and Nevada the regular gasoline is 85 octane, not 87. I burn the 87 octane mid-grade here to meet the 89 octane at sea level requirement in my 2016 6.4L. My home is at 6,000 feet altitude and the nearby roads are at 5,000 to 11,000. Unless one lives at high altitude then one may not know that engine fuel octane, furnaces, cooking, and horsepower are impacted by less atmospheric pressure. The lower octane requirements are not in the Ram owners manual, since it impacts a minority of the buyers. It is best to burn what the manual states, but 89 octane you will find is normally not even an option at the gas pump here.

I was shocked to get up by Telluride, CO on my last ADV Motorcycle ride and find that they had only one grade available... 85. I hadn't ever even seen that as an option before.

Though that makes sense at that Altitude, especially with modern EFI vehicles that can adjust timing and enrichment so accurately and quickly.

Though, just to make sure I don't lose any power at, particularly at the most critical times, due to the computer pulling timing due to sensing detonation or something, I always spend the extra couple of bucks when planning on working it hard; Particularly towing long, steep hills in incredible heat at, or BELOW Sea Level - Did it, over in Death Valley, CA or while running up and down the Sand Dunes over on the coast, like Pismo (Oceano Beach, CA).

Running light, and level, or know that I am going to just be commuting around a Urban area, I have on occasion also sampled the lower, 87 Octane stuff. It may just be my imagination, but when I did, it seemed that it gave me a very slight increase in MPG.

85 octane at Telluride's altitude is the best choice. I firmly believe that engines actually have equivalent power from the lower octane gasoline than the very highest octane (100 octane racing fuel). I wouldn't be surprised to hear that even the lowest octane gasoline could have the most power due to it has less additives than the highest octane rated gasoline. Petroleum companies won't state that though due they want the public to believe that the higher octane gasoline benefits engines. However, I know from over 45 years of car driving experience that higher octane fuel does not equate to more power, more benefits, more cleaning, or anything other than the following... The higher octane is required for high performance vehicle engines due to it prevents pre-ignition/detonation and that's it, but at higher altitude engines run in lower atmospheric pressure thus burning lower octane gasoline is usually more than adequate.

On the 6.4 engine if the lower octane fuel is run at lower altitude the engine computer will make timing adjustments to prevent pre-ignition. In Colorado not all towns are at Telluride's high altitude. Running 85 octane there is fine, but at 5,000 to 6,000 feet is where most of the major cities are located. So 87 octane is the mid-grade gasoline that I burn in the 6.4 in Colorado to get the most power without pre-ignition issues.

So why does my Challenger require 91...same engine... Similar HP...

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SublimeScatShakr said:

So why does my Challenger require 91...same engine... Similar HP...

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Its actually not the same engine just the same displacement.

https://www.allpar.com/mopar/V8/truck-hemi.html

Nick@GotExhaust said:

Its actually not the same engine just the same displacement.

https://www.allpar.com/mopar/V8/truck-hemi.html

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Thanks! Good info!

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