What fuel for 5.7

[DTru]

This is great info. Coming from Mercedes, this being my first truck, I’m always tempted to put 93 in my limited. Sounds like what you’re saying is that’s not only safe, but optimal?

Its going to vary by application. If you dont want to think about it much then just run the recommended 89 and be done with it. If you want to test how YOUR vehicle reacts to different octane then you can go as far as logging ST/LT knock with one of the tools or you can manually calculate your MPG difference between running 89 and 93 over a few tanks.

I have yet to see any 5.7 hemi in the "recommended" 0-2 ST and 0 LT knock range running anything less than 93. Whether the extra cost of the 93 is worth it is subjective.

 

[Willwork4truck]

Its going to vary by application. If you dont want to think about it much then just run the recommended 89 and be done with it. If you want to test how YOUR vehicle reacts to different octane then you can go as far as logging ST/LT knock with one of the tools or you can manually calculate your MPG difference between running 89 and 93 over a few tanks.

I have yet to see any 5.7 hemi in the "recommended" 0-2 ST and 0 LT knock range running anything less than 93. Whether the extra cost of the 93 is worth it is subjective.

Could always mix fuels, say 1/2 tank down use a higher octane then another 1/2 tank down use 89. That's what I do at Costco since they only have 2 choices...

 

[DTru]

Due to the high amount of variables, its better to get through a couple tanks to make a conclusion. Run 89 for two tanks and then run 93 two tanks while manually calculating MPG. The more data you gather the better.

 

[Gman]

...or don't. I really don't need to put that much thought into it. The truck runs great on Mid-grade. I don't notice any real difference running Premium. If I can get Premium at the Mid-grade price at Costco (and don't even have a Mid option), then I'll get that.

@Jamo237 - Which Mercedes are you coming from? I sold my 2016 GL 450 and got into my Limited as my first pickup/first FCA product. I only used Premium in that bi-turbo, but it really needed it. I'm happy to add more gallons of Mid-grade for the same cost as fewer gallons of Premium.

 

[DTru]

...or don't. I really don't need to put that much thought into it. The truck runs great on Mid-grade. I don't notice any real difference running Premium. If I can get Premium at the Mid-grade price at Costco (and don't even have a Mid option), then I'll get that.

Exactly what I said. If you dont want to go down the rabbit hole of tuning specifics to squeeze out that extra 1% then put in mid grade and enjoy your ride.

 

[Jackson67]

Can someone tell me what octane is recommended for the 5.7?
Thanks

89 octain

Can someone tell me what octane is recommended for the 5.7?
Thanks

89 octain is recommended for better fue economy and performance and 87 is acceptable.

 

[User_3336]

89 octain

89 octain is recommended for better fue economy and performance and 87 is acceptable.

89 octain?

 

[392DCGC]

2,910 miles on my truck so far, all 87 octane. Bought in March, so it had a few weeks of good cold weather to hurt the MPG average. 17.848 MPG average, 21.317 MPG best, 16.305 worst (cold weather). Do not bother referencing your screens for any really accurate measurements. My screen is usually off by .5-1.5 MPG from manually tracking it with Fuelly.

I will let you know once mine has been delivered. On my 5.7 Hemi Durango, I use 89 if 91 isn't available. When I went home to visit my mom in Indiana, they have 93 available .. I tried that and was grinning all the way up and down the street. Of course, that also has SPORT mode with paddle shifters, but even in regular mode, it was a whole new beast.

Others will argue that octane means nothing .. but I know the difference (just ask my Cobra).
I just say, buy what you can afford. If you can try higher octane for a tank or three, do it and see if you like it.
For the mileage I drive daily, I could get away with one of those overly priced electric vehicles

RECOMMENDED is for their stock tune and emissions to pass the EPA standards. (certain counties in Indiana you have to pass emissions prior to obtaining plates, etc.)

Tim N

Placebo effect dude. No way 91 octane magically woke up your 5.7 that isn't tuned for it. The 89 you were previously running must have been crap.

Could always mix fuels, say 1/2 tank down use a higher octane then another 1/2 tank down use 89. That's what I do at Costco since they only have 2 choices...

Not a bad idea for those who want to run 89 at Costco. But it's usually busy, and taking extra time to do this might **** some people off! lol. There's no reason to run over 89 in these trucks... if the engine isn't tuned for it, you're not doing yourself any favors, and may do worse for the engine.

 

[Willwork4truck]

2,910 miles on my truck so far, all 87 octane. Bought in March, so it had a few weeks of good cold weather to hurt the MPG average. 17.848 MPG average, 21.317 MPG best, 16.305 worst (cold weather). Do not bother referencing your screens for any really accurate measurements. My screen is usually off by .5-1.5 MPG from manually tracking it with Fuelly.



Placebo effect dude. No way 91 octane magically woke up your 5.7 that isn't tuned for it. The 89 you were previously running must have been crap.



Not a bad idea for those who want to run 89 at Costco. But it's usually busy, and taking extra time to do this might **** some people off! lol. There's no reason to run over 89 in these trucks... if the engine isn't tuned for it, you're not doing yourself any favors, and may do worse for the engine.

Not mixing at Costco, just alternating half tank fills there. Thats what I often do, especially if going up into the Piedmont range from near sea level. Coming down not so much.

 

[Diamondback]

89 octain?

cuz it's a PAIN .. lol .. run 91 on non-eTorque that is what I will do if I have to not take the eTorque to get the PanoRoof.

'course I'm bias cuz my Durango R/T likes 91 and loves 93 .. but I also paddle shift all the time, too.

 

[DTru]

2,910 miles on my truck so far, all 87 octane. Bought in March, so it had a few weeks of good cold weather to hurt the MPG average. 17.848 MPG average, 21.317 MPG best, 16.305 worst (cold weather). Do not bother referencing your screens for any really accurate measurements. My screen is usually off by .5-1.5 MPG from manually tracking it with Fuelly.



Placebo effect dude. No way 91 octane magically woke up your 5.7 that isn't tuned for it. The 89 you were previously running must have been crap.



Not a bad idea for those who want to run 89 at Costco. But it's usually busy, and taking extra time to do this might **** some people off! lol. There's no reason to run over 89 in these trucks... if the engine isn't tuned for it, you're not doing yourself any favors, and may do worse for the engine.

Get a tuner or logging system that lets you monitor your ST/LT Knock. I bet you 1,000 internet points that your engine is pulling timing due to knock on 89.

 

[Diamondback]

Placebo effect dude. No way 91 octane magically woke up your 5.7 that isn't tuned for it. The 89 you were previously running must have been crap.

If I run 89 in my R/T, I fill up every 10 days.
If I run 91 in my R/T, I fill up every other Friday (Payday).
I drive the same each and every day.
Engine is higher compression and tuned (it is an R/T).
The 93 was fun when back in Chicago & Indiana - I wouldn't use it every day unless I obtained an unlocked ECU and could tune it like I did my Cobra 11.1:1 with a laptop I had strapped in the passenger seat (I have a couple links in my signature.)
Where I live, they like using 10% Ethanol so that is what I have to use and opt for the 91. When you step on it, the engine responds. If I use 89, it is ok and you can tell it is retarding the timing to avoid pinging, etc.

I was wondering what you guys/gals use in your RAMs since they are HEMI's (and some are eTorques). Sounds like the 10.5:1 setup is "tuned" for the 89 and that is most likely what I will run since it is easier to grab at any gas station around here.

 

[RedRocketZ28]

Your Durango engine has the same compression ratio as the trucks, Diamondback. Was your Durango tuned for the higher octane fuel? Using the paddle shifters doesn't change anything either.

I've tuned every single GM vehicle I have owned via HPTuners. Have also been around and used aftermarket ECU's such as MS3Pro (Megasquirt) which my Camaro now uses. Most engines will get some form of knock from the factory (not audible) that shows up in logs. It didn't matter if I ran 87, 89, 91, etc., the high octane spark table was utilized 99% of the time.

Guys a lot smarter than us tune these vehicles from the factory to run on a specific grade of fuel, as you are all aware. They are usually pretty neutered from the factory to keep things safe and running a higher octane fuel isn't going to magically unleash more power unless someone tunes it to do so. Even then, picking up 10-15 rwhp from an N/A tune isn't going to be felt in an SUV or truck.

 

[Diamondback]

Thanks!
And I rarely use the paddles to upshift (just hit sport mode) .. I tend to use them to engine brake or hold the RPMs where I want to in turns, etc.

I'm not used to the MAP sensors, all mine have been MAF and easier for me to tweak the fuel mapping / VE.
Just some weird differences - but could be the software itself. I used HPT for my Camaros and SCT for the Cobra.
You just get used to one software then have to learn another.

Looking forward to getting this darn truck ordered so I can get closer to driving it!

(edit I see a lot of signatures with that fuelly link -- I'll sign up for mine once my truck gets here.)

Tim N

 

[Willwork4truck]

If I run 89 in my R/T, I fill up every 10 days.
If I run 91 in my R/T, I fill up every other Friday (Payday).
I drive the same each and every day.
Engine is higher compression and tuned (it is an R/T).
The 93 was fun when back in Chicago & Indiana - I wouldn't use it every day unless I obtained an unlocked ECU and could tune it like I did my Cobra 11.1:1 with a laptop I had strapped in the passenger seat (I have a couple links in my signature.)
Where I live, they like using 10% Ethanol so that is what I have to use and opt for the 91. When you step on it, the engine responds. If I use 89, it is ok and you can tell it is retarding the timing to avoid pinging, etc.

I was wondering what you guys/gals use in your RAMs since they are HEMI's (and some are eTorques). Sounds like the 10.5:1 setup is "tuned" for the 89 and that is most likely what I will run since it is easier to grab at any gas station around here.

with a laptop I had strapped in the passenger seat

The only fast cars that I've seen with a laptoip strapped down also have an optional light package in them, and I don't like seeing those...

 

[Diamondback]

with a laptop I had strapped in the passenger seat

The only fast cars that I've seen with a laptoip strapped down also have an optional light package in them, and I don't like seeing those...

LOL!!!!!

Where else can you drive triple digits and enjoy it and not get pulled over?

 

[silver billet]

I just filled my truck up with gas.
I put in 79.555 liters.
Cost of 87 octane = 113.9 c/liter
Cost of 89 octane = 132.9 c/liter

I put in 89 octane, so it cost me $105.
If I had used 87 octane, it would cost me $90.

Ouch. A difference of $5 I would grin and eat, but $15 every 2 weeks = $400 a year, just on the difference between 87 and 89.

I'm thinking I might just use 89 when pulling my trailer and put in 87 otherwise.

At one point I had a diablo trinity tuner for my Jeep with a 3.6 pentastar, and I thought it had a tune for 87 octane. I wonder if these hemis can be tuned that way? Maybe sacrifice a bit of engine power but make them run well on 87?

 

[devildodge]

Our local Rutter's has Non ethanol 90 grade.

I have used 87, 89 and this 90 non ethanol in my 2015 6.4l HD.

Right now I have 25 gallons of 90 with the remaining 7 gallons being a mix of last weeks 87, and the week before 89.

I have not noticed any major difference from the 3. Not sure which one I prefer. Not sure if running non ethanol is better or worse.

Last week was the heaviest I towed/hauled. I had about a ton of payload in the truck and about 6500 trailer. Went up the mountain camping and with 87 the truck performed just fine.

Today I am going on the same trip with mainly 90 grade. Last time I used it I didn't notice any real extra power or fuel savings.

Any thoughts on non ethanol 90 grade vs 89 grade 10% ethanol?

I am going on a long trip over 4th of July with just the truck and then a long trip the last week of July loaded for camping and towing camper.

Just curious if anyone wants to chime in with what I should fill up with?

 

[RedRocketZ28]

Run whatever makes you happy. I run 87 with 10% Ethanol in mine since that's what I can get the cheapest. I have towed over 2k miles with my truck and it performed as expected.

 

[Willwork4truck]

Run whatever makes you happy. I run 87 with 10% Ethanol in mine since that's what I can get the cheapest. I have towed over 2k miles with my truck and it performed as expected.

As opposed to the 3.21 vs 3.92 thread, I would admit to this issue being kinda’ “overthought” as long as a driver isn’t using 85, and it’s likely needless to run 91/93. As fuel goes up (Middle East tanker issues anyone?), it will make sense to run 87 more as long as you are not subjecting the truck to excess work.
Since most all fuel is ethanoled now, just keeping it down to 10% will be a challenge. I’ve seen the creep at local gas stations to run 15% now.