What gas should I use for my 21 BH?

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ozzyski

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Hi everyone,
Just got my first truck which is a 21 ram big horn, 5.7 HEMI. I upgraded from a 2015 Mitsubishi Mirage. My question is what gas am I supposed to use? Dealer said 89, and the 2 other ram owners that I know use 87 while other uses 93. The guy with 87 has a 19 Laramie 5.7 HEMI e torque, the guy who uses 93 has also a big horn but a 2020 for whatever it’s worth
 

G-Ride990

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I think the manual recommends using mid-grade or 89 octane. Doubt you would really notice a difference between any of the grades though. Other than your wallet of course haha. Basically, you want to run the lowest you can without getting spark knock.

Welcome to the forums!
 

HandyCruiser

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Until we traded the Charger Scat Pack for this Laramie, we had three vehicles that required 93 octane. That was fine when gas was cheap. But under this current government, it's getting harder to fill the tank. I can "detune" my Charger R/T Daytona and my high-boost PT Cruiser convertible to both run 87 octane. But I'm not buying an unlocked PCM for the Laramie and voiding the warranty on it.

We plan to run 87 octane gasoline in pure or almost pure form in the Laramie. After going through two 33 gallon tanks of fuel, it seems to be fine on Valero 87 octane cooked up in Memphis, TN. Our past experience was that the original 3.6L Pentastar engine was very sensitive to ethanol. So it ran better on pure 87 octane gasoline. But our 2017 Charger R/T was a beast and the 5.7 ran great on whatever we put in it. The engine makes enough timing adjustment to account for it. But that is the real problem. During everyday driving, the 5.7 Hemi has much more power than most people need. So if the PCM detects pinging and ******* the timing a few degrees, the driver likely isn't going to notice. The car or truck will run perfectly fine with enough performance to shoot down the road unimpeded.

***BUT***

If you plan to tow or race a 5.7 Hemi against Mustangs or Scat Packs with 93-octane 392 Hemi engines, you are going to need that extra power you are leaving on the table. The only way to know for sure is to run a science experiment. You will need an advanced OBDII reader and a cell phone or laptop with the right engine diagnostic app that can datalog. Then you drive and datalog the ignition timing retard. Start with 93 octane as your baseline, then burn a tank of 91 or 89 octane followed by 87 octane. This will tell you how the engine is reacting to the cheaper fuel. Since gasoline has many other qualities besides octane rating and ethanol content, you will not be able to depend on someone else's experiment unless they burn the exact same fuel from the same bulk plant and drive exactly the same way with exactly the same vehicle. You will need your own data.

For me, I figure the 87 octane with no or low ethanol will be fine since we won't be towing or hauling anything heavier than luggage. We might step up to 89 octane for trips in the mountains since I like to pass long lines of cars on curvy mountain roads. ;)
 
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RBJRBJ

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87 or 89 octane

My 2021 RAM Longhorn with a 5.7L Hemi and eTorque will run on both 87 and 89 octane. I’ve used both without any issues. That being said, I fill up using 89 octane regularly now and basically because the manual recommends 89 octane and with the 5.7L Hemi with eTorque gives me a little more peace of mind for long term use and driving.
 

Bigs

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I use what's recommended in the owners manual and put 89 in mine. Never tried 87. I wonder when I picked up my RAM what grade the dealer put in it? I'm willing to bet they put whatever the cheapest gas they had available.

89 octane here in my neck of the woods is +/- 1.50CAD a liter which should be around 5.67cad per gal (about 4.50usd). I bet you guys in the US still pay a lot less than we do here in Canada.
 

turkeybird56

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Asking what fuel to run is like asking which oil, air filter/setup or oil filter. I personally run 89. On a trip 4050 miles, got 22 hand calc on 89. I was also up and down mountains. The 87 tended to ping a lil, so I stay with 89. Heck, even my Stihl chain saw requires 89, lol. But yer wallet, do wat works for U.
 

HEMIMANN

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Top Tier Gasoline, non-ethanol if you can find it (keeps gas fresher longer, has higher power density).

Keep those new injectors and intake valve stems clean!

 

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