Octane

[farout75]

The same is true in the owners manual for the 5.7 89 they would like, but in 95,000 miles I have never used anything but 87. I get 17 to 20 mpg. I know there is a big difference between a 5.7 and a 6.4 so maybe what I've said is not applicable.

 

[jimmyfjk]

i have a 2021 model and my manual says to use 87 octaine

 

[HEMIMANN]

The difference in fuel consumption will show up mostly under load, i.e. - when towing. That's when load demand drives the advanced ignition timing.

3 different grades of gasoline are 3 different octane ratings, sometimes with different ethanol content. It has nothing to do with the long-since banned leaded gasoline. Harder working engines, such as the newer, small displacement, turbocharged 4 cylinder engines frequently mandate premium octane levels, as they have high combustion pressures that would knock (pre-ignition) with low octane level.

 

[Chilly Willy]

I have a 2020 2500 with the 6.4 Hemi and I run 92 non-oxygenated in my truck all the time! I notice it runs better than it does with 87 that is oxygenated since I drive my truck 2 maybe 3 times a week and put on less than 100 miles/week on average due to being an OTR truck driver! On trips out of state I will run 87 octane as it is usually the freshest available and I am usually refueling often enough so it doesn't cause issues!

 

[HEMIMANN]

In Minnesota it is illegal to run a 4 wheeled on-road vehicle with nonoxy gasoline. Corn processing lobby at it's finest. We've had to fight to keep the ethanol blending to 10%. They tried to raise it to 15%, but EPA cracked down on the lobby. Engine Manufacturer's Association is highly irritated at them.

They've also been pushing the 85% ethanol gasoline for those engines that are capable of using it. The alcohol solvency is so high that the fuel system requires more expensive elastomers that won't dissolve. The whole thing is ridiculous corporate welfare.

 

[MAC830203]

Torque management, higher compression(above 10:1) and the advanced timing on modified engines require 93+. It’s just a timing thing. The gear ratio you’ll notice a little on the highway. An older engine sometimes has deposits on the pistons causing an increase in compression, lots of detonation and a higher obtain is needed. I added **** injection for 30*+5 and 10.72:1 comp.

 

[Benson Wilde]

2020 6.4 and I have run all 3 ie 87,89 and 91 and no difference in mpg or how it runs. I just use 87 most of the time now.

Same here! I have a 2021 6.4 and used all three blends of gas, no difference in mileage and power.

 

[Irishthreeper]

Same here! I have a 2021 6.4 and used all three blends of gas, no difference in mileage and power.

Ditto. I have the same rig as OP but with 4.10’s. Our cross country trip this summer was all 87, no power issues or pinging and that was pulling about a 10,500 lb 5W.
And for the poster who made reference to the “elderly” maybe not hearing pinging….well…have a nice day, lol

 

[TomB 1269]

Never thought about it but at higher air temps it does make sense that higher octane would provide a measurable improvement over lower octane as the fuel charge will be at a higher temp and therefore more likely to detonate at higher temps therefore the ECU backs of the timing. Higher octane fuels "flash" slower and therefore burn more thoroughly and provide more power thru complete combustion. So at higher air temps where "knocking" or detonation is more susceptible it would make sense.

I will have to keep this in mind next summer and if I ever drive south.

 

[Forrest Alley]

Would non ethanol gas hurt the 6.4 engine, I my local Wawa sells Non ethanol i use it in the lawn mower and change saw. I have never looked to see what the octane rating is. But I have though about trying it in the truck. I never have because of the cost is higher than the 87 or the 89.

 

[392DevilDog]

Would non ethanol gas hurt the 6.4 engine, I my local Wawa sells Non ethanol i use it in the lawn mower and change saw. I have never looked to see what the octane rating is. But I have though about trying it in the truck. I never have because of the cost is higher than the 87 or the 89.

It will be absolutely fine....but you can just send that extra money to me...i like money

 

[Octane]

Where/how to get that 88 octane?

 

[retired]

Where/how to get that 88 octane?

move to Minnesota ....maybe some other corn controlled state.

 

[Octane]

move to Minnesota ....maybe some other corn controlled state.

I see no reason why the 88 would even be made.87 and 89 or 91 or higher ,yes.One point percentage is useless as far as performance would be. In the south we try to use corn properly...on the dinner plate with butter and a biscuit!

 

[retired]

I see no reason why the 88 would even be made.87 and 89 or 91 or higher ,yes.One point percentage is useless as far as performance would be. In the south we try to use corn properly...on the dinner plate with butter and a biscuit!

just a money maker for the corn farmers...our government at work....

 

[Octane]

So I guess it' s okay to burn our food as long as the planet doesnt burn in 12 years as some have said.A farmer shouldnt be a fuel corn alcohol supplier.An oil company shouldnt grow vegetables either....and most politicians shouldn't be politicians.

 

[392DevilDog]

Where/how to get that 88 octane?

In PA Rutters and Sheetz sell it at certain stores. I get mine at the Local Rutter's...i have given Sheetz enough of my money

 

[BigBassDude]

I always ran 89 octane in my 2018 6.4 3500 dually. When I moved to Wyoming this year I switched over to ethanol-free 89 and saw an average fuel economy increase of 2-3 mpg, as well as better engine performance. As an aside, from almost day one I always disabled MDS when I used the truck and saw essentially no difference in fuel consumption. MDS sucks (as we all know), but that is a topic for another thread. I just traded the 2018 for 2021 3500 SRW Cummins. The 2021 owners manual actually calls for premium gas in the 6.4! Not sure if they re-tuned the engine to make that necessary. Has anyone else seen that?

 

[HEMIMANN]

No. Nonethanol is preferred - it has higher energy density and non of the corrosive effects of alcohol. Like I said though, at least in our state it is illegal to dispense non ethanol gas into a car or truck. Due to the corn processing lobby having bribed our politicians to create this law for corporate welfare. Corn is food, not fuel.

 

[Dan Topp]

I’m willing to bet that the pcm or MAF will adjust timing for fuel air or octane,but with the lack of ethanol in my area nobody has an explanation of why 91 pure is slower burning then 93 10% ethanol that makes sense to a 93 tuned ram owner. Newer fuel systems are designed for eth or methanol