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Discussion Starter #1
Is it possible the quality between gas brand differ that much from your experience? It seems that my gas burns substantially quicker using the nearby grocery store brand gas (used to use Valero, that is a bit furthur away). I'm reconsidering now on going back w/ the Valero (or Shell, where I take the BMW/Audi/Honda). Both places I use 89 octane for the HEMI. Your experiences/conclusions/thoughts/etc.?

:cool:
 

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My gas mileage does seem to vary, depending on where I get it. Cheapo, side of the road stations tend to go quicker. I also get better gas mileage with the 87 octane than I do with the 89.
 

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I've found that out here, my mileage goes up when I use premium; the engine also runs better. As for brands, I use Costco, Shell and Valero with similar results.
 

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I get better mileage with 89 than 87...and yes, the manufacture does make a difference. maybe the refiner than the mfg eh? depends on additives and how often the retailer goes thru fuel. My Concord would not run on the off brand stuff.....it was bad.....
 

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We had a gas shortage here in AZ a few years back due to a pipe break, it was discovered that all almost all the stations in AZ get their gas from teh same place. All the gas is the same. Some stations add chems (Special branding) but the gas itself all cames from the same great big tank.
 

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BP, Cheveron, Shell have been the best for me. They also have techron.
 

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The location in the country also matters. Refineries have to make a special blend for California that they don't have to make for the rest of the country.
 

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UberCommander said:
busy gas stations mean cleaner gas.
OR cheaper gas, OR better access, OR more people drive that way....

I do not think most people are thinking about cleaner gas today.
 

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We have a place at the beach and down there, Ocean City MD, they use ethanol in their fuel (E10 I think). I get a drop in mpg when I fill up with that stuff.
 

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brand vs mileage

Yes ethanol will cut your mileage and that varies on amount and the engine itself to some degree. Also there are regional and state specifications which may in the end effect mileage a bit. As noted almost all refiners do wholesale to independents and in some cases other brand names if that company does not have a refinery or terminal in the area. Usually that becomes an exchange between refineries. the cheaper off brands often do not have the same additives even if bought at the same terminal. Additive packages are added while loading and can be turned on or off depending on the customer criteria. On any one tank this might not matter but can over time with potential injector fouling or other related issues. Some stations do not filter at the pump which can put you at some low risk of bad fuel.
 

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jeep63 said:
We have a place at the beach and down there, Ocean City MD, they use ethanol in their fuel (E10 I think). I get a drop in mpg when I fill up with that stuff.
Wow, thats a great point. I've always noticed the "This Contains 10% Ethanol" at my local Exxon, but never realized that is likely lowering my fuel efficiency, albeit very small.
 

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Discussion Starter #14
Aside from brands, are there any real world findings that entails octane rating effects MPGs as well? For the last two months, I decided to pump in just regular unleaded into my HEMI. It's a bit weird that the manuals says acceptable to use 87 octane, but it's optimal to use 89 octane. I basically downgraded b/c I don't exactly haul anything (aside from people at times) and I'm running a 4x2 XK as well. Any harm with this practice?
 

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Aside from brands, are there any real world findings that entails octane rating effects MPGs as well? For the last two months, I decided to pump in just regular unleaded into my HEMI. It's a bit weird that the manuals says acceptable to use 87 octane, but it's optimal to use 89 octane. I basically downgraded b/c I don't exactly haul anything (aside from people at times) and I'm running a 4x2 XK as well. Any harm with this practice?
No harm. I've been using 87 in mine since new except for a few tanks of 89, and I could tell no difference.
 

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i have alot of experience here and will try to take these the best I can:

#1. the petrol DOES all get mixed together when its in its raw form so therefore it is all the same...........to a point. Each brand will have its own "package" which does make it unique.

THe best, from a performance perspective has been CHevron with the worst (of the name brands) has been Shell.........

We figured this out quite some time ago while trying to tune out an LS1........we got the timing just perfect and all was good. THen latter it was pinging and the knock sensors we pulling out timing. YIKES!

While it did take us awhile we figure it to be bad gas........

We brought up our story on LS1Tech (forum) years ago and lo-and-behold this was rampid.

For the last 6 or so years we've known this and have seen this time and time again..........

#2. DOes 93 octane change mpg or hp vs 87 octane?

Well this can get complicated...............it depends on the motor. The HEMI has what is refered to as adaptives. This means our computer LEARNS not only the environment, but also your driving style, fuel type, and all kinds of habits.

It is possible to drive like an old ninny with 93 octane and switch over to 87 octane and still drive like a ninny and see no real if any gain or loss.........shift points stayed the same, your weight stayed the same, the effort needed was still the same, and energy needed to make said power was still the same.

THe only way a HEMI MAY save MPG with better quality fule is if the CPU sees this as a perminate "change". The adaptives crank the spark timing up...............thus gaining hp/trq. Because the vehical is now running at its optimum, the MDS kicks in sooner and stays on longer because it takes LESS effort to achieve the same amount of work................but to some degree we are splitting hairs.

The bigger question is if the amount of increased MDS mode, thus the savings, will amount to the increased cost of buying the premium fuel...????

#3. How about the flex fuel 4.7?

If we are ONLY talking about gasoline and NOT E85.............then I can not logicaly see how or why MPG would change anything..............not a measurable amount to post your scientific findings.

#4. But what about E85?

Alky burns cooler..............this is good. Alky burns cleaner............also good. However alky has a poor burn rate and your milage actually FALLS...........but the good news is performance is INCREASED!!!

I know I know i know.........this is about mpg and not mph.........pffft, whatever.

E85 is an interesting material and guys are using it to race now..........its cheap, its becoming easy to find, it burns cool which will control detonation and you can add a stupid amount of timing............the octane is something like 98 I believe

hope this helps
 

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I think I'll take this on,
Gasoline, as it comes out of the refinery is, with the exception of octane, the same, regardless of brand.
It will also destroy your engine if used in that form.
Each Tier 1 supplier (Mobil-Shell-BP-Exxon-Marathon, Well, you get it, the primary brands) has their own additive package that is added to the White gasoline as it is dispensed into the tanker, or direct pipelined to a retailer.
This package will have a specified amount of detergents,dye,carbon control compounds etc. In addition, each grade of fuel has a slightly different package, and finally, there are more than 50 different specifications depending on where the fuel is marketed due to EPA considerations.
Now, some retailers, Sams Club for instance, will be on contract with, say, BP for this year.
That means, BP will supply Tier 1 quality fuel for the duration of the contract.
Most of the chain retailers have this arrangement.
Often, the store manager(not the teenager!) will be able to tell you who this years supplier is.
So, in those respects GAS IS GAS, sorta.
As some have found out, sometimes a engine is brand specific and will operate best on a particular brand or grade. There are lots of theorys but nothing more.
Now comes the Tier 2 operations. These are the non-branded buy low type operations.
As I go along here, I need you to remember, gasoline has a freshness life, just like any other perishable.
Typically, white gasoline has fallen out of grade within 15 DAYS!
That means, even with the additive package, it can no longer be sold as a Tier 1 product.
Well, ya sure cant throw it out!
So, whats done is ,the gasoline is restabilized with liquid propane. This'll get about another 15 days.
So, thats what gets marketed out of the buy-low type retailer.
And that liquid propane does nothing for mileage or injector life.
So, in summation, GAS IS GAS,
But, what comes out of the pump isn't

Hope I didn't start too big a fire, this stuff is flammable,
lol ........Rob
 

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i think you hit the nail on the head................but didn't touch on the question if 87, 89, 93 or whatever will change mpg

TO some degree, my day job puts me right at the point that this is happening............the company here in Houston where it is dispersed is named Megellan Products and Pipeline Services.

THat Tier II that you speak of is managed largely by computer now-n-days................when a tanker leaves the yard, it doesn't come back with 1 ounce of gasoline in its belly..............he hits all his stops and fills all his contracts. Anything left is a mid-day route that comes in and the database applies the nearest tanker in its route to the person(s) bidding in that area. That driver will get his list with those address' as he's going.

In some cases that driver may not have enough to full-fill the needs of a particular station in which case that station had to bid out to several companies and may get 2 or 3 tankers in a day or two to meet his/her needs.

its a controled kaos for sure........
 

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Octane question was after my post. I one finger type.
That being said, Most will find best mpg occurs with lower octane ratings to a point.
That point is the moment you hear spark knock (wasted power stroke)
Your computer constantly adjusts ignition timing to point of knock. It can 'hear' the onset as a vibration through the block and retards timing to eliminate it.
However, Ignition knock and cylinder pressure knock are not the same.
Cylinder pressure knock occurs because the heat of compression and the low octane have allowed the fuel to pre-ignite. No matter how far the ignition is retarded, this will occur.
Your manual says 89 octane preferred, 87 is ok.
What they're saying is for all 345 h.p. you must use 89 so the computer can advance the ignition far enouph.
But if you chose to use 87, it won't knock, but it wont make the advertised hp either.
Actually though, thats usually ok because,if you're honest with yourself, you probably havent floored it for weeks anyways.
So, you're kinda wasting money by giving it 89.
If it meets your performance criteria on 87, I'd say, run it!

........Rob
 

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good points.......

when we start talking about performance in the time to come, ignition timing will be important esp to those looking for low end GRUNT of off-roading..........

I think you will play an important part to those discussions RObby because people will want to understand why and how to many of the things I share with them with respect to performance parts.

Usually when I explain to people that our parts are adding 100 hp yet gain 4mpg, their first reaction is "think I was born yesterday?"

But when we can discuss how and why thats taking place, they start to think its not so unbelievable any longer.................then they see it
 
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