How do different brand gasolines affect your MPG?

ThorSellsCars said:

Ive been told that Pilot and Sunoco use runoff gas or left over and it can have trace amounts of non-additive/non-gas such as minor amounts of water, I know for a fact while Pilot and sunoco are cheaper at times they do in fact have lower gas mileage because of this i have conducted a similar experiment in Knoville TN when i lived there for 3 years this was also seconded by locals and coworkers

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ThorSellsCars said:

from what i understand they buy leftover gas from gas stations and less then quality stuff thats like lets say shell is 100% quality they buy the stuff that didnt pass the bench mark its still fine and runs its just not up to the benchmark at least this is what i was told by master mechanics at peterbilt who spoke to drivers about it. It could be a perpetuated myth but i know i got less mpg from sunoco and pilot, however sunoco in that region is one of the last remaining places you can get 100% gas

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Lol on your Sunoco comments.

I guess those Nascar drivers prefer watery "leftover" gas.

As long as the gas you buy is the proper octane, the station is frequently used and the gas has the top tier detergent additive package (Sunoco does), it's all fairly similar. My tuned Civic has been run exclusively on Sunoco Ultra 93 (E10) for two years, and is doing quite well.

Moopy62 said:

2018 Sport Hatch 6MT Ktuned since Jan 18. The beauty of having Ktuned is that it did not impact the cars MPG. I run 93 Octane and regularly get 28/29MPG around suburbs and 38-40 MPG highway. I usually fill up at Wawa (a local gas/convenience store) or Costco never with any impact on MPG. However, every time I have gone to Sunoco my MPG drops dramatically (3 to 4 MPG). At first I thought maybe it was that particular location but I have filled up across the local region with the same effect.Has anyone experienced brand MPG differentials. Would love to know why this happens.

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All I can tell you is I put Shell premium pure gas (no ethanol) in mine after using up most of the original tank from the dealer. Pure gas provides 34.2 MJ of free energy per litre, whereas E10 provides just 33.2. E85 is a shitshow at just 25.6 MJ per litre. In technical terms, ethanol-free gasoline should provide the highest power output and best fuel economy.

FC3L15B7 said:

All I can tell you is I put Shell premium pure gas (no ethanol) in mine after using up most of the original tank from the dealer. Pure gas provides 34.2 MJ of free energy per litre, whereas E10 provides just 33.2. E85 is a shitshow at just 25.6 MJ per litre. In technical terms, ethanol-free gasoline should provide the highest power output and best fuel economy.

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You're mostly correct. And accurate for the factory tune. From a chemistry perspective and energy content... True. With that, the best fuel economy. Power is work, the conversion of potential energy to kinetic; chemical to motion. The system of the L15B7 when tuned for increased power output requires more knock resistance which is better served by ethanol. E30 will kick 93 Octane in the teeth on this platform. Physics is cool too.

IronFusion said:

You're mostly correct. And accurate for the factory tune. From a chemistry perspective and energy content... True. With that, the best fuel economy. Power is work, the conversion of potential energy to kinetic; chemical to motion. The system of the L15B7 when tuned for increased power output requires more knock resistance which is better served by ethanol. E30 will kick 93 Octane in the teeth on this platform. Physics is cool too.

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Of course. If you need a higher octane level, biofuel has higher octane, which is used to reduced knocks, so what you've said is also true. To be sure, any general comments are definitely referring to stock engines, unless the thread refers to something else.

A family member of mine works in the fuel pipeline business. He's made it clear that all gas is the same when it leaves the refinery. The brands that we all know and love/hate differentiate themselves only by additives added that define their brand. This also creates the premium pricing model that everyone refers to as, "top tier" fuel brands.

The real problem comes when fuels are mishandled or contaminated once the fuel leaves the brand storage towers. All things equal such as octane, ethanol content, etc., you should not see noticeable gas mileage differences no matter where you fill up. As someone already pointed out, a station that is clean, busy and has good storage and pumping equipment is the place you want to buy fuel.

TheHorse13 said:

A family member of mine works in the fuel pipeline business. He's made it clear that all gas is the same when it leaves the refinery. The brands that we all know and love/hate differentiate themselves only by additives added that define their brand. This also creates the premium pricing model that everyone refers to as, "top tier" fuel brands.

The real problem comes when fuels are mishandled or contaminated once the fuel leaves the brand storage towers. All things equal such as octane, ethanol content, etc., you should not see noticeable gas mileage differences no matter where you fill up. As someone already pointed out, a station that is clean, busy and has good storage and pumping equipment is the place you want to buy fuel.

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A long time ago I worked at a gas station and for that job I had to learn a lot about fuel that I'd rather not have rattling around my brain box for the rest of my life. I can back you up and say gasoline is chemically identical with the exception of the blend of ethanol and detergents and other additives as you have pointed out.

But... and like Jennifer Lopez, it's a big one..

My minivan was rated for 87 octane. It was an underpowered piece of s*** and I never put more than what I needed to get from point A to point B. In short, I just used a cheap gas (although it wasn't the cheapest available).

At 230,000 something kilometres, there was so much carbon buildup on the valves and they were so loud I had to get a BG intake cleaning done and it's like $120. Six months later the noise was back and it needed another treatment and it's simply because the gas is shit. Lol. It meets the bare minimum government requirements for detergents, but it's not enough.

Gas may be all the same from the refinery, but I will tell any person who asks: just buy a gas with more detergents to combat long-term effects. Of course GDI doesn't matter as much, but it's worth knowing the difference between what is the same and what's not.

Good post BTW.

Long story short, there is a huge difference. And fast forwarding to my own tuned Si experience, rotate Shell and Chevron ONLY. I have had serious issues with other brands and Knock Control/LSPI.

jeff2417 said:

Long story short, there is a huge difference. And fast forwarding to my own tuned Si experience, rotate Shell and Chevron ONLY. I have had serious issues with other brands and Knock Control/LSPI.

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Interesting so im minutely vindicated

jeff2417 said:

Long story short, there is a huge difference. And fast forwarding to my own tuned Si experience, rotate Shell and Chevron ONLY. I have had serious issues with other brands and Knock Control/LSPI.

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You seriously got super-knock??

FWIW The gas pumps in Ontario, Canada show the ethanol percentage for each grade, 87 octane is 5% 91/93 10% mid grade somewhere in between.
I've been using Indian Reservation gas for over 30 years with absolutely no issues. It is almost the only place to get ethanol free premium, the use of which is a good idea in direct injection engines to minimize intake valve gunk buildup. I'm pretty sure rez gas is mostly raw gas with no additives, or a crap shoot of whatever is cheap and available at any given time. So much for so-called tier one gasoline, which I consider so much hokum promoted by BMW because their direct injected engines are so prone to intake valve crud buildup and they need to blame someone for their bad design (VW is bad too) I have only noticed a change in fuel economy when using lower octane fuel; lower octane = lower gas mileage. ECU probably pulling back timing.

jokacz said:

FWIW The gas pumps in Ontario, Canada show the ethanol percentage for each grade, 87 octane is 5% 91/93 10% mid grade somewhere in between.
I've been using Indian Reservation gas for over 30 years with absolutely no issues. It is almost the only place to get ethanol free premium, the use of which is a good idea in direct injection engines to minimize intake valve gunk buildup. I'm pretty sure rez gas is mostly raw gas with no additives, or a crap shoot of whatever is cheap and available at any given time. So much for so-called tier one gasoline, which I consider so much hokum promoted by BMW because their direct injected engines are so prone to intake valve crud buildup and they need to blame someone for their bad design (VW is bad too) I have only noticed a change in fuel economy when using lower octane fuel; lower octane = lower gas mileage. ECU probably pulling back timing.

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Except Shell though because their premium gas is ethanol free in both US and Canada according to their website.

FC3L15B7 said:

Except Shell though because their premium gas is ethanol free in both US and Canada according to their website.

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Alas, there are no Shell stations anywhere near me in upstate New York.

They are across the border in Canada though, but the price of gas there has been absurd for years.

jokacz said:

Alas, there are no Shell stations anywhere near me in upstate New York.

They are across the border in Canada though, but the price of gas there has been absurd for years.

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Shell is definitely the usual suspect for expensive gas in general, but the irony is, the Shell I use is cheaper than Petro Canada, Husky and ESSO by far and usually only .03 cents more per litre than Pioneer (Regular). They are a really small Circle K with just two pumps (4 nozzles) and run out of gas frequently. I assume because they're 10¢ cheaper per litre than the other two closest Shells and have smaller tanks.

It is the Brand of “Foot” that obtains mpg.