What octane gas do you guys run

[GotGladiator]

Just 87, daily drives and even when towing. No issues.

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[TrainMan]

87 octane. 93 octane on special occasions (My Jeeps birthday, or maybe after an oil change.) I like to give it treats sometimes .

 

[XuanwuJT]

I was told at my dealership to use standard unleaded fuel for mine, so 87.

I also thought this was interesting.

 

[MrZappo]

Patently false. It’s 10.2:1. Up from 9.6:1.

General rule of thumb is 9.3:1 and below for 87. Jeep got this one wrong. Which is why the new 3.6s ping so much.

Yeah, "patently false". And "they ping so much*.

A little seriousness please.

These engines barely ping even a little bit if at all.

Ive heard a lot of good and bad about the pentastars and pinging "all the time" is not a common complaint even on this forum full of the most observant people on earth when it comes to jeeps.

Mine runs fine on 87. Every one i know with this engine runs fine on 87.

Maybe some dont. But either way, the only "patently false" thing is saying that all 3.6's ping. Not true.

 

[BLK HOLE]

Yeah, "patently false". And "they ping so much*.

A little seriousness please.

These engines barely ping even a little bit if at all.

Ive heard a lot of good and bad about the pentastars and pinging "all the time" is not a common complaint even on this forum full of the most observant people on earth when it comes to jeeps.

Mine runs fine on 87. Every one i know with this engine runs fine on 87.

Maybe some dont. But either way, the only "patently false" thing is saying that all 3.6's ping. Not true.

You just don’t know what you’re talking about.

They ping all the time. Most people just don’t know what they’re listening to.

 

[BLK HOLE]

I've never had pings in any car..regardless of octane. What brand of fuel are you using?

Most people don’t know what to listen for.

And you need your doors off.

 

[ShadowsPapa]

Probably placebo effect. Test it yourself have someone fill it without you knowing what they put in.
The rule of thumb is always run the lowest you can, as it has more energy per gallon. The additives that raise octane lower the amount of energy in the gas.
My wife's LR4 says to run premium but I tested that on a long road trip. 91 on the way down got 2 mpg worse than 87 on the way back, sure I didn't have all the power the engine could make on on 87 but we were going for efficiency.

No, it doesn't. There's no difference in energy content.
Higher octane fuel simply resists self-ignition. It doesn't burn faster, it doesn't burn slower, it doesn't have more or less energy. The only time you run into that is if the octane is raised mostly or in part by ethanol.
Check the sites that have facts about fuel.
There's also proof in dyno tests like some of us have.

Fine, don't believe me even though I've studied it for years - maybe check out what MIT says LOL ->

With slight variations — depending on the crude oil and the refining and blending processes used in production — all gasoline grades contain the same amount of chemical energy. When combusted, premium (high-octane) gasoline and the less-expensive (and less-glamorous) regular, and all grades in between, provide the same amount of thermal energy, or heat, which an engine uses to generate the mechanical power that moves a vehicle.

<- That was from MIT

Here's more from MIT - and all of this is basically stuff I've posted here a number of times when fuel talk comes up and the old urban legends and myths come out of the woodwork again -
More from MIT ->


There is, however, another aspect to this question, notes Ahmed Ghoniem, the Ronald C. Crane Professor of Mechanical Engineering at MIT: How much of that raw heat energy can the engine actually convert into mechanical energy? “One can argue that using high-octane fuels in the right engine ultimately leads to more mechanical power from the same amount of fuel,” he says.

In other words, higher-octane fuel confers an advantage in some cars, but not others. It allows performance-oriented engines (specifically, those with higher compression ratios) to burn gasoline at higher pressures and higher temperatures. These conditions at the moment of combustion create better thermodynamic efficiency, so a greater percentage of the gasoline’s heat energy gets converted into motive power.

Octane rating is a measure of grace under pressure: how evenly a gasoline will burn under difficult conditions, like hard acceleration. Ideally, the vaporized gasoline inside an engine’s cylinder burns by the propagation of a wave of flame, ignited by the cylinder’s spark plug. This allows a smooth transfer of power to the engine’s crankshaft and the car’s wheels. But at higher pressures or temperatures, small pockets of gasoline vapor can prematurely explode, or self-ignite, creating a distinctive “knocking” sound, as well as potentially destructive shock waves.

Gasoline with a higher octane rating does not self-ignite easily, and burns more evenly

 

[P.Lo]

Since day one off the lot, I've run premium 93 or Sunoco Ultra 94 when possible........... MPG always around 22.0.
Engine runs smooth as silk for over 30K miles now.

 

[ShadowsPapa]

You just don’t know what you’re talking about.

They ping all the time. Most people just don’t know what they’re listening to.

Wow, where'd you get that?? That's more bunk.
Ping is the sonic wave resonating in the combustion chamber walls when two flame fronts collide. That ping is the result of DETONATION and is almost always destructive. It blows away the cooler boundary layer from the top of the piston, it damages spark plugs, it breaks things.
They don't always ping. I have no idea where you get that, but as a professional mechanic, I can tell you - they don't - or they'd sure as hell better not.
Detonation is when the fuel SELF-IGNITES. The normal flame, started by the spark plug, progresses across the combustion chamber. As the flame front progresses is shoves the unburned mixture into a corner, so to speak. The pressure and thus heat increase in the unburned fuel until it finally ignites, creating another flame front. When the two collide, you get a sonic boom of sorts, and that makes the cylinder walls ring - the ping sound. It's destructive.

Don't tell me I don't know what to listen for - I'm college and factory trained and worked in the field for years. I've built and repaired engines since I was a teen in the 70s.
I know ping - here's a result -

Since day one off the lot, I've run premium 93 or Sunoco Ultra 94 when possible........... MPG always around 22.0.
Engine runs smooth as silk for over 30K miles now.

Then you'll like the quote from an MIT engineer I posted about "premium" fuel.

 

[MrZappo]

You just don’t know what you’re talking about.

They ping all the time. Most people just don’t know what they’re listening to.

Thanks, ill file this in my "random internet genius smart guy who knows more than the rest of the world" folder.

Maybe your ears ping and its not the engine.

 

[BLK HOLE]

Wow, where'd you get that?? That's more bunk.
Ping is the sonic wave resonating in the combustion chamber walls when two flame fronts collide. That ping is the result of DETONATION and is almost always destructive. It blows away the cooler boundary layer from the top of the piston, it damages spark plugs, it breaks things.
They don't always ping. I have no idea where you get that, but as a professional mechanic, I can tell you - they don't - or they'd sure as hell better not.
Detonation is when the fuel SELF-IGNITES. The normal flame, started by the spark plug, progresses across the combustion chamber. As the flame front progresses is shoves the unburned mixture into a corner, so to speak. The pressure and thus heat increase in the unburned fuel until it finally ignites, creating another flame front. When the two collide, you get a sonic boom of sorts, and that makes the cylinder walls ring - the ping sound. It's destructive.

Don't tell me I don't know what to listen for - I'm college and factory trained and worked in the field for years. I've built and repaired engines since I was a teen in the 70s.
I know ping - here's a result -

Then you'll like the quote from an MIT engineer I posted about "premium" fuel.

I’m a professional mechanic too.
They ping. But GREAT copy and paste.


Use 93.

 

[BLK HOLE]

Thanks, ill file this in my "random internet genius smart guy who knows more than the rest of the world" folder.

Maybe your ears ping and its not the engine.

You just don’t know what you’re taking about. Pretty common.

 

[ShadowsPapa]

I’m a professional mechanic too.
They ping. But GREAT copy and paste.


Use 93.

HAHAHAHA - copy and paste. Right. I wrote papers and articles on this topic. The only thing I copied and pasted was what I pasted from MIT - the post you quoted from me is my knowledge on the topic from years of research, and training others. No copy/paste, I typed it from what I know.

What a hoot.

 

[Bucephalus]

FWIW. I live in Miami and when we get bad hurricanes[cat 3+] we lose power for days on end. Generators are our best friends. They're made to run on 87. But we fill them with 93 because they run for an extra 60min-90min depending on load.

 

[ShadowsPapa]

>> With slight variations — depending on the crude oil and the refining and blending processes used in production — all gasoline grades contain the same amount of chemical energy. When combusted, premium (high-octane) gasoline and the less-expensive (and less-glamorous) regular, and all grades in between, provide the same amount of thermal energy, or heat, which an engine uses to generate the mechanical power <<

Likely then another SOURCE for the fuel because again, 87 and 93 contain the same energy, produce the same BTUs when burned. The first sentence could explain some differences depending on when and where the fuel was purchased. Also too many variables in the anecdotal information posted in this thread about how much more energy is supposedly in high octane.
Scientifically, it just isn't true. So there are other explanations in play.

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