What gas are you using?

[jbehrn]

I usually fill up at Costco, but with the last two tanks in my new Rubicon I’ve been running Chevron regular. I have noticed it runs smoother with the Chevron gas. What is everyone else using and have y’all noticed any difference in mileage/performance from one gas company to another? For Rubicon owners, what is your average mileage?

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[Motoarch]

Whatever's available and cheap when I need gas.

Never noticed a difference.

 

[Tiny]

Well kroger gives me the best discount so I get mine there while getting groceries LOL! If I'm out on the road I look for shell, don't know why I just always have. I've not noticed a lick of difference in different fuel brands personally.

 

[Rein89]

For the most part if you are shopping gas within a certain area, all the gas is the same. The only differences being additives and variables from the specific store. Some places will add water into the tank, or just never clean the tanks. It's so hard to really determine differences when gas shopping. Find a place you trust that runs well in your vehicle. Stick to the recommended octane level, and you'll do fine.

 

[Mr._Bill]

I run 87 octane from Sam's Club. I occasionally fill up at Smith's (Kroger). When traveling, usually Flying J, Pilot, or a local Costco or Sam's Club, depending on where I am. I don't notice any difference in how it runs.

 

[Jeeperjamie]

BP or Shell station. I can use my getupside app there and get cash back. Made back over $150 this year alone so far.

 

[johnparjr]

Sams Club mostly because they are cheaper as gas prices here in CA are crazy high

 

[FREEZE451]

91

Averaged 18.5 today on a 160 mile journey - mainly 60-70 mph.

37" Ridge Grapplers
2" Mopar lift
4.88 gears

 

[Free2roam]

Doesn't matter. My buddy and I used to commute 134 miles round trip 6 days a week. We tested Arco, BP, Chevron, and Shell and all the way down to the cheapest gas we could find. Two different vehicles. One a 4 cyl Civic. One a Chevy S-10 V6. He swore up and down that Chevron was far better. I called BS. In the end all that he had done was prove he was paying more for gas at Shell and Chevron. We got no better gas mileage on any of the more expensive fuels. No less on the cheaper ones. They are all the same. My other buddy drove fuel big rigs for years. I asked him what he did when the ground tanks were full. He said they usually dump it in the other tanks. 87/89/91.

 

[Jeeperjamie]

Also I run regular 87 octane gas in mine. I got a Max Tow with 4.10 gears and the wife and I was able to get the MPGs up to 18.9 today on our way back from the beach. I'm running 37 12.5 17 Goodyear kevlar MTRs.

 

[Dan in Pasadena]

Whatever's available and cheap when I need gas.

Never noticed a difference.

I totally agree. I’ve got a relative who is a total tight ass about every kind of expense but he insists he gets better mileage with Shell or Union 76 gas. I say that’s a crock. I buy 67 octane regular at my local ARCO and my truck runs absolutely fine.

In my cammed LQ4 producing maybe 375 HP and I don’t know how much torque I run premium but I’m pretty sure if I ran regular in it, it would run fine.

 

[ShadowsPapa]

For the most part if you are shopping gas within a certain area, all the gas is the same. The only differences being additives and variables from the specific store. Some places will add water into the tank, or just never clean the tanks. It's so hard to really determine differences when gas shopping. Find a place you trust that runs well in your vehicle. Stick to the recommended octane level, and you'll do fine.

Add water? LOL. That's pretty 1970s conspiracy, isn't it?

Most of the time you won't see differences enough to make them run differently -but then again, my 70 would not ping on Walmart premium while it would on certain other premiums - all in the same area. (it was a high compression 390)

Since 1995, the Environmental Protection Agency (EPA) has required a minimum level of deposit control additives in gasoline. However, eight major automakers felt the EPA didn’t go far enough to keep engines running cleanly. In 2004, they released a TOP TIER (TM) gasoline standard that provides superior deposit control by requiring more and better additives. TOP TIER certification also mandates that the enhanced additives be used in all grades of fuel marketed by a company, and that those fuels be sold at all of the company’s retail locations in the U.S. and Canada.

But there are some differences even comparing 87 to 87 or 91 to 91. I've posted it before, maybe I can find my notes again.

 

[DanW]

I usually fill up at Costco, but with the last two tanks in my new Rubicon I’ve been running Chevron regular. I have noticed it runs smoother with the Chevron gas. What is everyone else using and have y’all noticed any difference in mileage/performance from one gas company to another? For Rubicon owners, what is your average mileage?

I run mostly Shell regular. Occasionaly, I'll run Mobil or Phillips 66, or other Top Tier certified fuels in our area like Sunoco or Country Mark. I wish we had Chevron around. I like them as well as I like Shell. My JK 3.8 runs better on both of those.

 

[DanW]

Btw, all the stuff about gas coming from the same refinery has some truth and some BS to it. The truth is, in a given area, they usually do come from the same refinery. But the BS is that they are completely the same from Shell to say, Speedway. They are not. The additive packages are different. Shell, Chevron, Mobil, etc. have their own proprietary additive packages. For example, Chevron uses their own Techron add pack. Some are better than others. Some MUCH better than others. Fuel distributors offer different packages, too. For example, they usually offer a package to achieve Top Tier detergent requirements.

So they are not really the same.

As for mileage, I doubt anyone has the ability to drive exactly the same from tank to tank, so it isn't really that easy to tell a mileage difference without some pretty sophisticated equipment that none of us have. It's an educated guess, at best. But what will make a difference is the quality of fuel used over time. Obviously fuels that keep key parts cleaner will ultimately have a fuel economy advantage. B

And btw, what does premium 92 or 93 octane do with the Pentastar? It gets you about 3hp, tops. But it does run slighly smoother, for a reason I barely understand, but it involves the timing of combustion in relation to the piston stroke, I believe. (But I may be explaining it incorrectly) That's straight from a guy who was one of the Pentastar's designers. As for me, I can't tell a difference in HP or smoothness, at all, from 87 to 93. So I don't run it. How does he know? He had millions of dollars in testing mileage and equipment that can easily show that kind of data during testing/development. Interesting stuff.

Guess what fuel is most commonly chosen by auto manufacturers for EPA testing? Chevron.

 

[ShadowsPapa]

And btw, what does premium 92 or 93 octane do with the Pentastar? It gets you about 3hp, tops. But it does run slighly smoother, for a reason I barely understand, but it involves the timing of combustion in relation to the piston stroke, I believe. (But I may be explaining it incorrectly) That's straight from a guy who was one of the Pentastar's designers. As for me, I can't tell a difference in HP or smoothness, at all, from 87 to 93. So I don't run it. How does he know? He had millions of dollars in testing mileage and equipment that can easily show that kind of data during testing/development. Interesting stuff.

The results depend on engine design and tuning.
Burning the charge takes time. You want peak combustion pressures at about 14 to 16 degrees ATDC. That's when the rod angle and crankpin position give the most mechanical advantage in turning the crankshaft. So you time the spark to ignite the charge so you reach the burn point of peak combustion pressures at that time. Higher RPM means there's less time to burn the charge so it has to be lit sooner - advance the ignition timing.
The problem with higher compression engines is that when you ignite the charge sooner, the advancing flame front has time to force the unburned part of the charge into a corner, so to speak. That raises the pressure - and temperature - and the remaining unburned mixture self-ignites.
Ping
So timing is backed off and may not hit that peak number of degrees of rotation.
Higher octane resists self-ignition under heat and pressure. So you can go ahead and send that spark sooner, light the charge sooner, and the fuel will resist self-ignition. More power - but don't look for a seat of the pants increase.

My own 360 peaks out HP and even torque at 38 degrees BTDC timing. More and it's burning and pushing back on the piston as it's still coming up. You lose HP with too much timing, and lose with timing too retarded.

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