Better MPG with higher octane?

[mmondich]

2021 Ram 1500 5.7HEMI eTorque. Has anyone has run 87 octane and noticed a significant change when switching to a higher octane? I know the manual says no lower than 89 but other than MPG potentially being impacted, I don't have any issues. Would possibly spend the extra $$ if I knew it would yield higher MPG's. Thanks.

 

[Timeless]

Like others, I notice about 1 MPG difference when keeping the octane at 89 or higher.

Basically 14s when on 87 and 15s when on 89+

 

[CRAIG4FSU]

Like others, I notice about 1 MPG difference when keeping the octane at 89 or higher.

Basically 14s when on 87 and 15s when on 89+

I went from 15 to 16 MPG. As noted though it's about .35 - .40 cents a gallon difference between 87 and 89 octane.

 

[mikeru82]

I haven't noticed a difference between the two to be honest. I usually go with 89 though since, at 10 cents/gallon more than 87 it's less than 3 bucks difference when I fill up. But I have no problem going with 87 in a pinch.

 

[Idahoktm]

I thought I was done running 89 octane fuel in my truck, but after reading a few more comments about the pros and cons, I decided to run an experiment. I ran two tanks with 87, back-to-back and two with 89. The difference in mileage between the two octanes was negligible. All four tanks ranged between 17-17.5 MPG with a 80/20 city/highway mix. I got 17.5 and 17.3 MPG with 87 and 17.3 and 17.0 MPG with 89.

At this point I'm really having a hard time believing that I will ever get better economy with 89. However, I have noticed that my truck is in Eco mode more often with 89, so I think I'll continue to run it. I don't get any knocking or pinging with 87.

As far as the fuel computer goes...I see a lot of complaints ( I know, odd for a forum ) about its accuracy and notice that a lot of you call it the lie-o-meter. I hand calculated all four tanks after each fill-up. The most the computer was off was .35 MPG and on the last tank my hand calculation showed 16.95 MPG and the computer showed 17.0. It's safe to say that I'm done with hand calculations.

 

[Whoa_Ram]

I thought I was done running 89 octane fuel in my truck, but after reading a few more comments about the pros and cons, I decided to run an experiment. I ran two tanks with 87, back-to-back and two with 89. The difference in mileage between the two octanes was negligible. All four tanks ranged between 17-17.5 MPG with a 80/20 city/highway mix. I got 17.5 and 17.3 MPG with 87 and 17.3 and 17.0 MPG with 89.

At this point I'm really having a hard time believing that I will ever get better economy with 89. However, I have noticed that my truck is in Eco mode more often with 89, so I think I'll continue to run it. I don't get any knocking or pinging with 87.

As far as the fuel computer goes...I see a lot of complaints ( I know, odd for a forum ) about its accuracy and notice that a lot of you call it the lie-o-meter. I hand calculated all four tanks after each fill-up. The most the computer was off was .35 MPG and on the last tank my hand calculation showed 16.95 MPG and the computer showed 17.0. It's safe to say that I'm done with hand calculations.

My computer is usually high by about 1-1.5mpgs on every fill up. Don’t know why but it’s never that close lol

 

[Tnseltim]

I always get my gas from Costco, premium is about the price of regular elsewhere so I get the good stuff. I’ve tried the 87 two different times and I got about 1.5 mpg less on both tanks.

 

[Eminclake]

I see better mileage w/ Chevron/Exxon but both are out of my way for regular fill ups so it negates any advantage. When towing my race trailer I notice about 1-2 mpg better using 89 vs 87.

I like reading this! A 2,400 round trip to Florida hauling a 14' wedged cargo trailer yielded me only 8.4 MPG loaded, 8.9 MPG return trip and empty. I was using 87 and every one in a while I experienced some knocking, but not enough to be annoying.

 

[ferraiolo1]

I tried 87/88/89 on my last almost 1600 mile trip. There were non differences in mpg between them during my fill ups, and the hand calculated mileage was within .4 of my trip average.


21.5 mpg was my overall average. 88/89 had less initial engine ping when the accelerator was pushed.

This is with A.S.S off and MDS disabled, from north central pa, across the state, down into Kentucky and tenn, then back across tenn, up through Virginia back to pa. So lots of mountains doing around 70-80 most of the time

I’ve been sticking with 88 since it’s the cheapest of the three options.


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[Mountain Whiskey]

Most who think there is a big gain from using a slower burning fuel (higher octane) do honestly feel this gain. This feeling comes as justification for the money spent.

This is no different than many physical mods people do to thier cars or trucks. Spend hundreds of dollars on something that has a horsepower claim of 50, is really about 1.5 and it is the best thing ever! It has to be, they just blew a wad of cash on it.

 

[theblet]

It just helps when towing heavy for me. Otherwise same

 

[ferraiolo1]

Eh not exactly how it always works if you look at timing tables and knock sensors.

You can clearly hear pinging when you put the engine under load with 87.


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[Buz]

Most who think there is a big gain from using a slower burning fuel (higher octane) do honestly feel this gain. This feeling comes as justification for the money spent.

This is no different than many physical mods people do to thier cars or trucks. Spend hundreds of dollars on something that has a horsepower claim of 50, is really about 1.5 and it is the best thing ever! It has to be, they just blew a wad of cash on it.

Agreed. But (maybe it's just me) I think i do feel the truck accelerates more smoothly under LIGHT to MODERATE acceleration with 91 vs 87. You know when you ask the engine for power but not so much that it downshifts? That's when I feel the smoothness with 91 vs a little more 'choppiness' with 87.

 

[RAM Patriot]

Using a higher-octane fuel allows an engine to take advantage of an ideal timing curve without causing detonation. Once that timing has been achieved, there is no advantage to using higher-octane fuel. That is why I use 89 as recommended by Mopar.

 

[theblet]

i use 87 because the manual says its acceptable, unless I'm towing heavy.

 

[1awesomelaw]

Using a higher-octane fuel allows an engine to take advantage of an ideal timing curve without causing detonation. Once that timing has been achieved, there is no advantage to using higher-octane fuel. That is why I use 89 as recommended by Mopar.

View attachment 108821

So 89 it is always going forward, even with an E-Torque motor? just checking.....

 

[gHiDoRa]

So 89 it is always going forward, even with an E-Torque motor? just checking.....

Yes.

 

[RAM Patriot]

So 89 it is always going forward, even with an E-Torque motor? just checking.....

Correct...

 

[silver billet]

Eh not exactly how it always works if you look at timing tables and knock sensors.

You can clearly hear pinging when you put the engine under load with 87.


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You and I can hear the difference, apparently, but some feel if they don't hear it it doesn't exist

You're not going to notice a difference in two tanks, I get completely different MPG everytime I fill up, doesn't matter what I do. Maybe some always drive the same trip identically, with the same head/tail winds, the same tire pressure, the same speed, the same traffic, but I definitely don't.

The only way you will definitely prove a difference, is by data logging from the computer. When you see that pinging showing up on the cheap gas far more than on 89, that's the proof. And when you get pinging, you get reduced MPG, that's a mathematical certainty.

I don't run 89 hoping to get a bump in MPG, that's just a bonus. I just don't want my engine working against itself, and I definitely shudder when I hear it doing so.

 

[GKIII]

You and I can hear the difference, apparently, but some feel if they don't hear it it doesn't exist

You're not going to notice a difference in two tanks, I get completely different MPG everytime I fill up, doesn't matter what I do. Maybe some always drive the same trip identically, with the same head/tail winds, the same tire pressure, the same speed, the same traffic, but I definitely don't.

The only way you will definitely prove a difference, is by data logging from the computer. When you see that pinging showing up on the cheap gas far more than on 89, that's the proof. And when you get pinging, you get reduced MPG, that's a mathematical certainty.

I don't run 89 hoping to get a bump in MPG, that's just a bonus. I just don't want my engine working against itself, and I definitely shudder when I hear it doing so.

I personally just use 89 all the time since I run under heavy load enough that it would just be a major pain in the *** to plan 87 vs 89 for my fillups.

And yes, I can hear the pings. I don't care what anyone says, that's not good for your motor.

 

[ram813ltd]

this debate goes on in every vehicle forum and has been for decades. any higher octane than what the manufacturer recommends is a waste of your money. and the mpg computer in your vehicle could be right and could be wrong. same as using fillups/miles. fuel tanks never fill the same. the other is people still doing oil changes every 3000miles/3 months whereas manufacturers recommend 5k, 7.5k, or in the case of RAM no more than 10k miles (that even surprised me). i'm thinking manufacturers know more about what they produce than any forum reader.
but if it makes you feel better have at it.