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monoloco
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Location: Pescadero BCS
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| Quote: | Originally posted by David K
captkw, while I have always used 87 octane regular in my V-6 Tacoma (as recommended by Toyota)... I did try using Shell and Chevron Premium on a
recent road trip and gained 1-2 mpg increase over using Costco, ARCO, and 76 Regular on the same driving conditions and cargo.
Is it more of an ethanol content thing than an octane thing, if Costco/ARCO has more ethanol than Shell or Chevron?
I am now comparing Shell Regular to Costco Regular for city driving.
I know that ethanol-free PEMEX increases my mileage the most... Isn't better mileage (using less fuel) important anymore vs. burning corn (food) in
our cars? |
The higher the ethanol, the lower your milage will be because ethanol has less energy density
than gasoline.
"The future ain't what it used to be"
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captkw
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Posts: 3850
Registered: 10-19-2010
Location: el charro b.c.s.
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Mood: new dog/missing the old 1
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| Quote: | Originally posted by captkw
I wished it was One easy answer...ITS Not!! I do a lot of study and try my best to be update and informed..but the past two years .......its been
change by the week...Lots oF PLAYERS IN THE FEILD AND AS OF today the Midwest with its GMO corn is really pushing the ethanol !!! I can say without
any problem that in a marine motor run mid top grade fuel...in a car depends on so many factors ......but...think about it... hard to wrong with TOP
SHELF !! |
Trying to a save buck with cheap parts,,oil and Fuel is false ...in the long run IMO...just like
buy cheap fishing gear= you get what you pay for......................Sorta !!
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Fatboy
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Old Topic but what the heck.... I always seem to get better MPG's from Pemex gas than California's gas.
There seems to be less difference between Arizona/Nevada/Utah as compared to Pemex.
Octane seems to be misunderstood to a certain degree. It is not a marketing ploy as Bob implies, it does actually make a difference, but he is
probably correct that most of us are just 'throwing' away our money using higher Octane.
Of course 'PREMIUM' fuels may more contain more detergents and stabilizers along with a Higher Octane number so it may be worth it.
HIGHER OCTANE FUEL IS LESS VOLATILE THAN LOWER OCTANE FUELS. In other words it is harder to ignite and possibly slower burning.
As fuel is compressed it also has a rise in temperature. If you continue to compress gasoline at some point it will ignite without any spark. In a
diesel engine that is what you want.
In a typical gasoline engine you want the spark to ignite the fuel at a set point in engine rotation (timing) or else you get the dreaded knock as the
fuel starts to burn on its own.
Since all cars have varying degrees of compression, some vehicles will compress the fuel more before igniting it with the spark. Up to a certain point
the further you compress the fuel before igniting it the more power you will get out of the fuel.
Now it is clear that lower compression engines will not knock on lower Octane fuel. Higher compression engines need higher Octane fuel to avoid
knocking.
Most common vehicles on the road today would be considered 'lower compression' vehicles so buying higher Octane fuel is not needed.
Now things are never as simple as that and in this case, as stated earlier, almost all vehicles made in the last 25 years have a Knock Sensor.
The cars onboard computer monitors the Knock Sensor and adjusts the engine, usually, by retarding the timing whenever it determines that knocking is
happening.
When you retard the timing you also decrease power output, so all your vehicles that 'run fine' on 85 or 87 octane might be doing so at the expense of
power output.
If you tow or live in mountainous terrain you might want to experiment with a higher Octane fuel. You might get better mileage and/or better
performance with higher Octane fuel.
For light loads, city driving for example, a lower octane may be fine. You need to experiment with different Octane fuels for your vehicle.
Now aside from Octane which is JUST the relative ease of a certain fuel to burn - lower octane=easier burning, higher octane=harder to burn, there is
also the matter of how much 'energy' is in the fuel and Ethanol certainly decreases the energy content, but so do other factors.
According to the EPA the energy content varies as much as 8% depending on the season and the producer.
It would therefore be possible to for Shell, Chevron, Mobil or some other name brand fuel to have 8% more energy in each gallon of gas which would
certainly result in better mileage such as DavidK reports.
Gasoline might be one of Americans largest expenses that we have no way of knowing what we are getting except by advertising and gut reactions. We
have no easy means to determine good/better/best between the all the gas stations we drive past every day.
Maybe fuel mileage should be expressed in miles per cents and not miles per gallon. So if I spend an extra 20 cents per gallon at Shell but go an
extra 2 miles is it worth it?
Here is a comparison ....
Arco is $3.00 per gallon and you get 15mpg with it.
Mobil is $3.20 per gallon and you get 16mpg with it.
Mobil is $3.20 per gallon and you get 17mpg with it.
Which is cheaper per mile...
Arco @15mpg =20 cents per mile
Mobil @16mpg = 20 cents per mile
Mobil @17mpg = 18.8 cents per mile
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55steve
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Location: Warner Springs, CA
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Quote: Originally posted by Fatboy  | Old Topic but what the heck.... I always seem to get better MPG's from Pemex gas than California's gas.
There seems to be less difference between Arizona/Nevada/Utah as compared to Pemex.
Octane seems to be misunderstood to a certain degree. It is not a marketing ploy as Bob implies, it does actually make a difference, but he is
probably correct that most of us are just 'throwing' away our money using higher Octane.
Of course 'PREMIUM' fuels may more contain more detergents and stabilizers along with a Higher Octane number so it may be worth it.
HIGHER OCTANE FUEL IS LESS VOLATILE THAN LOWER OCTANE FUELS. In other words it is harder to ignite and possibly slower burning.
As fuel is compressed it also has a rise in temperature. If you continue to compress gasoline at some point it will ignite without any spark. In a
diesel engine that is what you want.
In a typical gasoline engine you want the spark to ignite the fuel at a set point in engine rotation (timing) or else you get the dreaded knock as the
fuel starts to burn on its own.
Since all cars have varying degrees of compression, some vehicles will compress the fuel more before igniting it with the spark. Up to a certain point
the further you compress the fuel before igniting it the more power you will get out of the fuel.
Now it is clear that lower compression engines will not knock on lower Octane fuel. Higher compression engines need higher Octane fuel to avoid
knocking.
Most common vehicles on the road today would be considered 'lower compression' vehicles so buying higher Octane fuel is not needed.
Now things are never as simple as that and in this case, as stated earlier, almost all vehicles made in the last 25 years have a Knock Sensor.
The cars onboard computer monitors the Knock Sensor and adjusts the engine, usually, by retarding the timing whenever it determines that knocking is
happening.
When you retard the timing you also decrease power output, so all your vehicles that 'run fine' on 85 or 87 octane might be doing so at the expense of
power output.
If you tow or live in mountainous terrain you might want to experiment with a higher Octane fuel. You might get better mileage and/or better
performance with higher Octane fuel.
For light loads, city driving for example, a lower octane may be fine. You need to experiment with different Octane fuels for your vehicle.
Now aside from Octane which is JUST the relative ease of a certain fuel to burn - lower octane=easier burning, higher octane=harder to burn, there is
also the matter of how much 'energy' is in the fuel and Ethanol certainly decreases the energy content, but so do other factors.
According to the EPA the energy content varies as much as 8% depending on the season and the producer.
It would therefore be possible to for Shell, Chevron, Mobil or some other name brand fuel to have 8% more energy in each gallon of gas which would
certainly result in better mileage such as DavidK reports.
Gasoline might be one of Americans largest expenses that we have no way of knowing what we are getting except by advertising and gut reactions. We
have no easy means to determine good/better/best between the all the gas stations we drive past every day.
Maybe fuel mileage should be expressed in miles per cents and not miles per gallon. So if I spend an extra 20 cents per gallon at Shell but go an
extra 2 miles is it worth it?
Here is a comparison ....
Arco is $3.00 per gallon and you get 15mpg with it.
Mobil is $3.20 per gallon and you get 16mpg with it.
Mobil is $3.20 per gallon and you get 17mpg with it.
Which is cheaper per mile...
Arco @15mpg =20 cents per mile
Mobil @16mpg = 20 cents per mile
Mobil @17mpg = 18.8 cents per mile
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You have the right answer!
Most people think that high octane fuel is better or 'hotter' but in reality it's 87 octane with additives to control the burn for use in higher
compression engines.
All my vehicles run fine on 87 and the only time I've ever had an engine ping was on returning from a trip to Gonzaga bay, I refueled at an Arco in
Calexico and had minor pinging climbing the grade up 8 toward San Diego. I believe that I get better mileage on Pemex but don't have any definitive
data to prove it.
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Fatboy
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Registered: 6-28-2005
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Personally I do not like ARCO which is funny because I will go to little Mom & Pop gas stations all day but it has been 20 plus years since I went
to an ARCO.
Need to check my mileage on some 'better' brands of gas since a 1 mpg increase can pay for a 20 cent swing in my example.... it might be worth to
spend more.
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David K
Honored Nomad
Posts: 64739
Registered: 8-30-2002
Location: San Diego County
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Mood: Have Baja Fever
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This was a year old thread, and I did a much more complete comparison between Premium and Regular fuel driving between San Diego and Tucson. I
actually got slightly better mileage on 87 octane regular than 91 octane premium. Used Shell and Chevron gasoline. So no reason to pay more for
premium if the vehicle is designed for regular.
This was in my 2010 V-6 Tacoma Double Cab. Except for the mountain in California between San Diego and Ocotillo, the rest of the drive is mostly level
across the desert.
Here is part of my post on Tacoma World, just 3 months ago:
I drove the signed speed limit or within 2 mph. It was 65 & 70 in California and 65 & 75 in Arizona (with a short 55 section). I topped off
before the highway drives, so no in town driving was included.
Going to Tucson on 91 octane I got 18.3 and 18.4 MPG with my two fill ups. Adjusted for the odometer error it is closer to 18.8 and 18.9 MPG.
Going back to San Diego area was on 87 octane I got 19.6 and 17.7 MPG with the two fill ups. Adjusted for odo error it is 20.1 and 18.1 MPG.
19.10 MPG avg. on regular 87 octane.
18.85 MPG avg. on premium 91 octane.
So close as they are nearly identical, but the better figure is regular grade gas, even if they were the same... no reason to buy premium.
The gas in Arizona is about 50 cents a gallon cheaper than here and the pumps there (as they do here) are labeled as containing up to 10% ethanol.
This is the best mileage I have recorded (Tucson to Yuma) beating the previous 19.2 mpg I recorded in Mexico using ethanol-free Pemex gasoline (87
octane). I was heavily loaded for camping and driving fast. Under similar conditions as I just drove, I believe with Pemex, I would be well over 20
mpg.
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Fatboy
Senior Nomad
Posts: 735
Registered: 6-28-2005
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David what about between Shell/Chevron ect and Arco? You hinted at better mileage based on that change...any such change?
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rts551
Elite Nomad
Posts: 6699
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Kinda hard to buy Shell/Chevron in Baja. And seldom do I see a PEMEX sign in USA. Makes any kinda comparison mute doesn't it?
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David K
Honored Nomad
Posts: 64739
Registered: 8-30-2002
Location: San Diego County
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Mood: Have Baja Fever
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| Quote: Originally posted by Fatboy | | David what about between Shell/Chevron ect and Arco? You hinted at better mileage based on that change...any such change? |
It is a tough call... at least among people I communicate with offline, the thinking is that ARCO has the most ethanol and thus the lowest MPG.
However, all pumps in SoCal have the "May contain up to 10% ethanol" sign. In Arizona I saw the same signs, so it isn't just a stupid California
thing. It seems ARCO has 10% and the others not so much?
For a while I was seeing lower MPG numbers from Costco gas as I had using ARCO, and that's why I went to Shell (I was getting up to 20 cents a gallon
discount using my Ralphs Card... in Az the Ralphs stores are called Frys and the discount is at 76 stations.). That discount made Shell gas close to
the price of Costco gas.
Recently I have seen Moshen fuel trucks delivering at Costco. Not sure if it is that or just a seasonal change in the blend, but my mileage on Costco
gas did improve the past few months. Around town driving going from 14/15 to 15/16 mpg.
-----------------------------------------------------------------------------------------------------
The question was Premium vs. Regular, and a year ago I replied my findings, so I am responding with August 2014 research that showed me there was no
advantage to paying the higher price for premium. The final paragraph includes the numbers on PEMEX MAGNA (87 octane) I recorded from El Rosario to
Oceanside a couple years ago. Based on the different driving conditions, I conclude that PEMEX provides better MPG economy than any gasoline sold
here. The reason would be NO ETHANOL diluting the gasoline.
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Fatboy
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| Quote: Originally posted by rts551 | | Kinda hard to buy Shell/Chevron in Baja. And seldom do I see a PEMEX sign in USA. Makes any kinda comparison mute doesn't it?
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I do not know....I used to be close to empty after driving from Phoenix to San Luis and I would fill up after crossing the border. Same thing coming
back from San Felipe I would fill up prior to crossing back into the states.
But now with the larger difference in price I usually fill up on the US side. When you break it down by cost per mile it makes a difference.
The last time I kept detailed figures I was getting 10% better mileage (almost 2 mpg more) using Pemex. So I could save $10 to $15 on those two fill
ups with no 'extra' effort.
Fill up now before crossing or fill up after crossing? For $10 and a little thought it is a no brainer.
I am not 'going' out of my way to save this money either.
Now you can say the driving is different in Baja but just looking at the Phoenix to San Luis and the San Luis to Phoenix portions I always used less
fuel getting home than going down and it is as close to identical driving as you can do and about 220 miles each way.
In 2012/2013 I did this trip 9 times probably saved closed to a $100...Heck I seen people drive miles to save 3 or 4 cents on a gallon of gas! And
when gas was $3.50 a gallon that is 1%!!!!!
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David K
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Posts: 64739
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Location: San Diego County
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Thank you Fatboy!
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rts551
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yes. Iv'e seen people drive miles to save a penny after they reviewed their detailed records
filling up before or after the border is a no brainer and does not require detailed records...nor does it have anything to do with the majority who
cross infrequently. makes for god posting though.
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Terry28
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You guys have way too much free time on your hands!!!!
Mexico!! Where two can live as cheaply as one.....but it costs twice as much.....
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dasubergeek
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I only use Shell or Chevron in the US... I filled up at one of the few Arcos that has diesel near me and it was full of gunk, blew my fuel system
apart. That was a fun repair.
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