87 Octane is OK for 6.4L Hemi?

[Crusty old shellback]

 

[jadmt]

Noone should keep any gas sitting in the tank of any vehicle longer than 3 months unless treated with some form of fuel stabilizer which I do since my vehicles sit a while too. I always use Startron to preserve fuel and when I want to remove carbon buildup and clean up the fuel system I also use Seafoam.

Doesn't matter what octane you use because ethanol is your enemy.

so I just talked to my buddy who actually mixed the fuels at the bulk plant for the last 30 years and he said for the last several years, he said he believed since the 90's anyway that all fuel gets stabilizer at the truck rack (his terminolgy) and no additional stabilizer is needed he said it has been this way for a long time. He also said the only fuel that takes a little hit from sitting too long is if you have winter blend in a really hot climate as the butane will vent off but in reality not a big deal. He said there are actually 4 seasons for gasoline and winter blend is the lightest due to the amount of butane which is added to help cold starts. I asked how long would he leave gas before he would worry about it and he said "I dunno maybe a year" He also said of all the fuel Cennex has the highest standards. He also said all costco fuel west of Mandan is Cennex and cennex octane will always be higher than what is on the pumps.

 

[BigDaddyKong]

The only time I would not run 87 is if I was towing a heavy load, especially in mountains.

 

[jetrinka]

I once thought the 6.4 in these trucks required higher octane. Until l was told to go re-read my manual..... It gets 87 now and runs just fine with no mileage impact (as if mileage matters here anyway lol)

 

[jsalbre]

I once thought the 6.4 in these trucks required higher octane. Until l was told to go re-read my manual..... It gets 87 now and runs just fine with no mileage impact (as if mileage matters here anyway lol)

The manual for the 2019s and first half of 2020 said to run mid-grade, so there was definitely some confusion before.

 

[Kauffmj1]

The manual for the 2019s and first half of 2020 said to run mid-grade, so there was definitely some confusion before.

I just took delivery of my 2023 Powerwagon this Monday and checked the manual since this topic seems to pop up from time to time. In the 2023 manual, it only mentions running 87. No mention of running 89 at all. Odd that its changed in such a short time. Maybe they re-mapped the tuning for 87 on the later trucks?

 

[Ionicbrick]

I just took delivery of my 2023 Powerwagon this Monday and checked the manual since this topic seems to pop up from time to time. In the 2023 manual, it only mentions running 87. No mention of running 89 at all. Odd that its changed in such a short time. Maybe they re-mapped the tuning for 87 on the later trucks?

Thats good to hear. Part of the reason I went diesel was the cost of putting premium in my 2015 6.4 since I was always towing. Being able to go 87 helps a little. And if you’re towing on occasion that 6.4 is a perfect beast.


Sent from my iPhone using Tapatalk

 

[Big Tom]

My 2017 2500 ran great around town with 87 but I ran mid grade when towing as per the manual. When Costco opened a fuel station near me Premium became less expensive then 87 elsewhere. so I ran that around town.
Truck ran much better on premium. I never heard a Ping no matter what I ran.....

 

[whitexc]

Thats good to hear. Part of the reason I went diesel was the cost of putting premium in my 2015 6.4 since I was always towing. Being able to go 87 helps a little. And if you’re towing on occasion that 6.4 is a perfect beast.


Sent from my iPhone using Tapatalk

Us gas folk don’t hear this from the diesel crowd often! Not sure if perfect beast is the right nickname for the 6.4 but I will take the compliment!!!


Sent from my iPhone using Tapatalk

 

[Gondul]

The manual for the 2019s and first half of 2020 said to run mid-grade, so there was definitely some confusion before.

2018 manual recommended 89 'for optimal performance' but states 87 was acceptable...
Like @Big Tom, Costco Premium is cheaper than Plus so I ran that for a while...
I saw no appreciable difference in mileage/power/engine noise between the 87 or the 91 from Costco.... ¯\_(ツ)_/¯

 

[Ionicbrick]

Us gas folk don’t hear this from the diesel crowd often! Not sure if perfect beast is the right nickname for the 6.4 but I will take the compliment!!!


Sent from my iPhone using Tapatalk

As a guy who put 110k on a 6.4 pretty well pushing it to its limit, I loved my truck. Don’t get me wrong, I love my diesel too. But the 6.4 is no slouch. If you tow a camper or boat once per month or so within spec, the 6.4 is THE perfect match of power, reliability and maintenance for you.

I tow 5-8k EVERY day, AND tow 11k monthly for camping. The diesel is a better fit for someone like me. I was getting worse mileage and having upkeep issues since I was working that 6.4 so hard.
But what a great motor.

For someone who wants power when they need it, but ease when they don’t. The 6.4 is the perfect beast.


Sent from my iPhone using Tapatalk

 

[Crusty old shellback]

As stated in the video I posted.
Unless you are hearing pinging, no reason to run a higher octane fuel. No improvement is there.

Clifnotes of the video, 87,91,110,and 116 octane ran in the motor. All were within 1 HP of each other.

Octane is just a number of how well it helps prevent pinging (predetonation).

 

[JohnandDonna]

The owners manual for my 2020 says 89 octane preferred, but 87 octane is acceptable. I feed mine a straight diet of 89 octane. No problems at all.

 

[Dave01]

I started out running 89 when I first got mine .... then went to every other tank ..... now am running 87 and hear no pinging, certainly no lack of power.

Crusty summed it up well in his post. I'd add to his pre-detonation comment that higher octane in years past also prevented engine run-on, or dieseling. Not a factor in our injected, highly computer optimized fuel systems.

 

[PCT]

The manual for the 2019s and first half of 2020 said to run mid-grade, so there was definitely some confusion before.

Are we 19-mid 20ers to ignore that and run 87? Is there a slight difference in tuning from factory that would be different?


Sent from my iPad using Tapatalk

 

[Dave01]

Are we 19-mid 20ers to ignore that and run 87? Is there a slight difference in tuning from factory that would be different?


Sent from my iPad using Tapatalk

I doubt there is a difference in tune in those years, but don't know that for sure.

I think maybe the question is this ... is the only thing we are concerned about an audible pinging? If so, I'd say ok to run 87 even in those years and if you hear no pinging, you are ok. If we are concerned about other factors that aren't audible then that's a different story. To me other than pinging the only thing that could happen "behind the scenes" is the engine management sensing something in the fuel and backing off timing, which would affect power but not so sure most of us would notice it.

My non-expert opininon, after a fair amount of reading on this subject, is that we are fine running 87 in a 6.4.

 

[Wichita Dave]

I've been running 87 octane in my 2022 2500 6.4L 410 axle for about 10K miles. I recently switched to 89 it runs and sounds so much better I'm going to keep buying it. And I do try to buy top tier gasoline. I mostly use the truck to tow an 11k gvw 5th wheel

 

[sstoner911]

Am I reading that correctly in the manual? Hemi's always needed minimim 91 octane.

Is this correct? Even for towing a 8k lb. RV?

Yes when it comes to the 6.4L. I had a Scatpack and the manual said 91 octane only. I am guessing they are tuned the same way for the HD trucks just as they are in the Scats.

You could try a lower Ocatane - but I bet you find it doesn't like it.

 

[sstoner911]

I've been running 87 octane in my 2022 2500 6.4L 410 axle for about 10K miles. I recently switched to 89 it runs and sounds so much better I'm going to keep buying it. And I do try to buy top tier gasoline. I mostly use the truck to tow an 11k gvw 5th wheel

Yup the 6.4 wants the higher Octane due to its tuning. You can find tunes for the 6.4 that will allow for E85 in the ScatPacks - not sure if that kind of tuning is available in the HD trucks. I knew guys adding superchargers to the Scats and running E85....

 

[jetrinka]

Page 477 in my owners manual

"FUEL REQUIREMENTS — GASOLINE ENGINE While operating on gasoline with the required octane number, hearing a light knocking sound from the engine is not a cause for concern. However, if the engine is heard making a heavy knocking sound, see a dealer immediately. Use of gasoline with a lower than recommended octane number can cause engine failure and may void or not be covered by the New Vehicle Limited Warranty. Poor quality gasoline can cause problems such as hard starting, stalling, and hesitations. If you experience these symptoms, try another brand of gasoline before considering service for the vehicle. 6.4L ENGINE Do not use E-85 flex fuel or ethanol blends greater than 15% in this engine. This engine is designed to meet all emissions regulations and provide satisfactory fuel economy and performance when using high quality unleaded gasoline having a posted octane number of 87 as specified by the (R+M)/ 2 method."

The 6.4 in the high performance cars is a much different animal than the truck engines.

You won't get any pre-ignition and even if you did it would automatically pull timing much faster than you'd ever hear anything. The days of distributors and hearing a can of rocks in the engine due to improper timing (on stock engines) are long gone.

Run 87, save money, be happy. Don't overthink it.