What fuel for 5.7

[Zeronet]

Do you expect more ignition problems under the load of towing?

When towing and more load on the engine I would want the highest performance and low probability of preignition. Don’t want the knock sensors retarding timing. Thus at least 89 for me when towing.

My current engine is recommended to use 87. It runs well on 87 when towing but in a few rare lower rpm situations I can feel the engine struggle for a second. I don’t get that with 89. If I run 91 or 93 when towing I notice a black soot in the tailpipe that I don’t get running the lower octane fuels and no further improvement in performance or mileage. That kinda tells me it doesn’t burn the premium fuel as well/thoroughly. So even though the recommended fuel is 87 (and that’s what I run everyday) I prefer to use 89 when towing. Just my experience.

 

[Ortiz7983]

Is your 87 straight gas and 89 10% ethanol? That alone would explain the mpg loss.

Who sells pure gas? I only put shell. Maybe I’m putting in the wrong thing.

 

[Gman]

It sounds like you've got a good understanding of what works for your truck and how you use it. Of course all of these numbers are relative to where in the country you are and the temperatures where you're driving. Our grades are 85, 87, and 89.

Who sells pure gas? I only put shell. Maybe I’m putting in the wrong thing.

Some stations pride themselves in selling non-blended gas. Ethanol blends can be problematic in some boat motors and power equipment. I don't know of any around here that sell it, but I also haven't researched it.

ETA: I found this site: https://www.pure-gas.org/

When I look in Colorado, I'm not surprised that several of these locations are marinas where there are large lakes/reservoirs.

 

[Ortiz7983]

It sounds like you've got a good understanding of what works for your truck and how you use it. Of course all of these numbers are relative to where in the country you are and the temperatures where you're driving. Our grades are 85, 87, and 89.



Some stations pride themselves in selling non-blended gas. Ethanol blends can be problematic in some boat motors and power equipment. I don't know of any around here that sell it, but I also haven't researched it.

So am I not suppose to put shell fuel in the ram? Since I believe it says it may contain se ethanol. Will that be bad for my engine?

 

[Gman]

I hope we're not taking this thread back to where it started. Ethanol blends are fine up to 15%. The question is being asked because the EPA rating is based on pure gasoline. Ethanol has less energy per volume than gasoline, so you can't expect the same numbers as the EPA estimate running ethanol blends.

Just because you had better/worse mileage while running a specific octane gasoline doesn't mean the octane is the reason for the difference. You have to compare based on the makeup of the gas that you're putting in the tank. Straight gas would make the octane comparisons easy. The "Contains Up to 10% Alcohol by Volume" adds a variable (and you know E-15 is 15% alcohol).

 

[Ortiz7983]

Off

I hope we're not taking this thread back to where it started. Ethanol blends are fine up to 15%. The question is being asked because the EPA rating is based on pure gasoline. Ethanol has less energy per volume than gasoline, so you can't expect the same numbers as the EPA estimate running ethanol blends.

Just because you had better/worse mileage while running a specific octane gasoline doesn't mean the octane is the reason for the difference. You have to compare based on the makeup of the gas that you're putting in the tank. Straight gas would make the octane comparisons easy. The "Contains Up to 10% Alcohol by Volume" adds a variable (and you know E-15 is 15% alcohol).

off topic, where do you find the born date on your vehicle?

 

[Gman]

The certification label on the drivers side. It's in a MMDDHour format.

 

[Zeronet]

It sounds like you've got a good understanding of what works for your truck and how you use it. Of course all of these numbers are relative to where in the country you are and the temperatures where you're driving. Our grades are 85, 87, and 89.



Some stations pride themselves in selling non-blended gas. Ethanol blends can be problematic in some boat motors and power equipment. I don't know of any around here that sell it, but I also haven't researched it.

ETA: I found this site: https://www.pure-gas.org/

When I look in Colorado, I'm not surprised that several of these locations are marinas where there are large lakes/reservoirs.

So if your grades are 85, 87 and 89 in Colorado and the owners manual recommends 89 what would you run? Does the octane requirement vary based on altitude? Just curious as I hope to make it out there in the next couple of years.

 

[Gman]

There's less oxygen per volume at our elevations. On the downside, we generate fewer horsepower. On the upside, there's not as much of a problem with unintended detonation.

I typically run what the manufacturer recommends for the engine. My previous vehicle required premium fuel since it recommended at least 89 octane (liquid intercooled twin-turbo V6).

I wouldn't be at all surprised if the Hemi is happy with 85 octane here. I plan to check it out later.

 

[Ortiz7983]

The certification label on the drivers side. It's in a MMDDHour format.

Thanks

 

[Goatmann]

The certification label on the drivers side. It's in a MMDDHour format.

can you explain the hour format? my hour is 06, is that 0600?

If it is, i hope 6am is a good time for a truck to be built/completed!

 

[Gman]

Yeah, it's a 24 hour clock. Mine was built in hour 15, or 3pm.

 

[runamuck]

I run 87 in mine. seems to run great. when towing I run 89.

 

[MJP]

I run 87 in mine. seems to run great. when towing I run 89.

I've tried 87 and 89 and havent noticed a difference.

 

[jmagsho]

Personally, I run nothing but 93 in mine, but then again, I own a Sunoco station. Mopar is recommending the 89 for a reason, so that's what I would use otherwise.

 

[louz]

My truck gets better gas mileage on 93. That's what I'm sticking with.

 

[runamuck]

probably thought higher octane would give me a boost when towing. maybe less likely to ping.

 

[Bsteiner36]

Anyone else get gas at Costco? We only have 87/93. The price difference is minimal too me and the 93 is cheaper than other gas stations 89 ( also Costco is top tier vs non ). I just want to make sure 93 won't affect my engine or how it rides. If price is not an option which would be better to run?

 

[Jingtao]

we have only 87/91 at Costco here. tried 87 & 91. 87 more louder or noisy, 91 quiet & smooth... stick with 91 from now, feel better

 

[Gondul]

Anyone else get gas at Costco? We only have 87/93. The price difference is minimal too me and the 93 is cheaper than other gas stations 89 ( also Costco is top tier vs non ). I just want to make sure 93 won't affect my engine or how it rides. If price is not an option which would be better to run?

COSTCO gas is Top Tier rated so either is good, but yeah, I'm currently running the 93 as well as it is cheaper than the 89 at every other gas station. So far seeing an increase in mpg, but still too early to tell as I've only run 3 full tanks (+1 tank to clear out the old gas) and I'd like to run at least 6 and a couple of long distance trips on the interstate.