who sells the best gas?

Much of the fuel is distributed from the same depots, so in a given area you can get the same gas at station A and station B. There are some differences in fuel additives from one brand to another, but all are required to meet standards. You will find some regional differences so YMMV.

Tom

 

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That's all true and all, but I still can't explain the 3-4 MPG increase I get using Shell gas. In my mileage logs over at CleanMPG I have the first 3 tanks on el cheapo gas and averaged like 54 MPG or something. On the 4th tank I put in Shell gas and got over 57 MPG, then on the tank right after that I put in Kroger gas and got my worst mileage ever 53.11 or so. All the ones after that are Shell. The 2 following the lowest mileage are deceiving since I think one didn't fill up all the way, which is why one is like 65 and the other is like 55.

I was doing some calculations one day when I bought some expensive gas without realizing it, $.17 more expensive actually. I figured that 3.5 MPG better mileage meant that even at $.17 more expensive that it was still worth buying. 60 MPG can get me 660 miles and 63.5 MPG can get me 698.5 miles. 38.5 extra miles is over half a gallon I save, really close to 2/3rds actually. 2/3rds a gallon costs about $1.80. So buying 11.667 gallons at el cheapo costs $31.50 and buying 11 gallons at that Shell cost $31.57. I uses gas prices as they are now, which is why the Shell one still works out more expensive. Back when I bought it gas was over $3 a gallon, it's down to $2.70 now. Anyways, that's assuming the 3-4 MPG increase is still true.

If someone can explain my 3-4 MPG increase using Shell then I'll be happy to listen. I've used Kroger, Walmart, Chevron, and QuikTrip and they all get less.

 

<div class='quotetop'>QUOTE(Alexstarfire @ Aug 3 2007, 07:28 AM) [snapback]489882[/snapback]</div>

I'm also looking at density as a predictor of performance:

 

<div class='quotetop'>QUOTE(christet @ Aug 3 2007, 06:58 AM) [snapback]489865[/snapback]</div>

From an MPG point of view, if you could find gas with no ethanol in it, you would get the best results.

 

<div class='quotetop'>QUOTE(Alexstarfire @ Aug 3 2007, 07:28 AM) [snapback]489882[/snapback]</div>

I find it interesting that you assume the mileage difference for your last 2 Shell fill-ups is due to an early shut-off but that the variance at the cheaper stations is due to inferior quality gas. I also find it interesting that you believe that Shell gasoline is better at the same time that I'm seeing lots of Shell commercials on TV claiming that Shell gasoline is superior to all others.

I have lots of reasons that you could be getting different mileage:
Different pumps at different angles.
Different Pumps that shut off at different times.
Different temperatures give a different density of fuel so a different volume of fuel.
Different temperatures so different fuel mileage from your Prius.
Different driving conditions.

If you really want to see if Shell gasoline gives you better mileage your need to do a repeatable experiment. You need to drive a set course repeatedly at a set speed with a set volume of gasoline in your tank.

My Uncle drove a tanker delivery truck delivery gasoline from the regional depot to local gas stations. All the stations received the same gasoline, Shell included. The only difference was that after he topped off the tanks for some of the "premium" stations he would pour a colored die into the tank to give the gasoline the correct colored tint. (If you notice Shell has a different colored gasoline that other brands) So while you may claim that you get better mileage with Shell, you can see why I would find that hard to believe.

 

<div class='quotetop'>QUOTE(jhinton @ Aug 3 2007, 11:18 AM) [snapback]489968[/snapback]</div>

My methodology is to record the fuel consumed versus the ICE shaft energy. My Graham scanner records fuel injector timing, ICE rpm and ICE torque. I use the rpm and torque over time to calculate the output energy in Joules. I use the injector timing and ICE rpm to calculate the fuel burned. I then divide the shaft output energy by the grams of fuel to get the energy per gram of fuel.

To make sure the same power range is used, I go to a local hill called Brindley Mountain. The drive over takes about 20 minutes at speed of 45-65 mph. As I approach the base, I set the cruise control to 55 mph and then mark the data at the same entry and exit points. The data between the marks is used to calculate the Joules per gram.

Successive fillings indicate the data is reproducible and testing at 70F and 90F also gives similar results. The only variable known to have an effect is the brand of gasoline and at higher power settings, 93 seems to work slightly better:




Bob Wilson

 

<div class='quotetop'>QUOTE(jhinton @ Aug 3 2007, 12:18 PM) [snapback]489968[/snapback]</div>

Look, I never said I understood it, I just said it happened. BTW, I know that those 2 are from the pump not shutting off properly because one was WAY over my MFD average by like 3-4 MPG, and the other was way below it, like 8 MPG or so.

I do basically drive the same places on each tank. And it's summer so the temp has been high. Last tank probably only had an average temp of like 80F or lower though. The first ones are at a lower temp, but that 1 shell tank inbetween all those others is what makes me wonder. MY MPG has only really been increasing, though stating to go down a bit cause of temps. At the time of the first Shell fill-up the temps were still going up, which means that the tank right after it had a higher average temp than the last one.

Like I said, I don't understand it, but it remains to be there. I can go fill up my next tank with some Kroger gas if you want me to post the difference, if any.

 

<div class='quotetop'>QUOTE(christet @ Aug 3 2007, 05:58 AM) [snapback]489865[/snapback]</div>

I just ask that anyone who possibly can, avoid BP.

Legislators in my former home state of Indiana decreed that the BP facility on the shore of Lake Michigan would be allowed to dump more chemicals into it. Residents of Illinois and Michigan are a little perturbed by this, especially when you get your drinking water from the lake and kind of like to enjoy it for recreation.

But hey, it created 80 whole jobs so who cares what anyone else thinks? :angry:

 

Well, I went to a Shell at my last fill-up (after reading all the positive reviews here) and I've taken a major hit in MPG. I had been getting around 53MPG with Marathon gas and now I'm lucky if I can get away from 48 MPG. I even checked the air in my tires to make sure that that wasn't the problem!

 

All of the raw fuel in a region may come from the same refiner, but there are differences in the additive packages. The name brand gasolines do have better additive packages to help keep your fuel injectors and the rest of your fuel delivery system cleaner. Quick trip gasoline is on the list of "Top Tier Gasolines. (www.toptiergas.com) I am sure the "no-name" gasolines try and keep their costs low by putting in the "minimum" additive package that meets requirements. However, the big name gas companies, especially the ones that meet the "Top Tier" standard have better additive packages.

I do not think it is possible to compare quality of gas by measuring mpg from on tankfull to the next. There are way too many variables in driving style, traffic, ambient temp, number of stoplights hit, mood of the driver, and on and on.

 

I wouldn't be surprised if some of the discount feul outlest take leftovers from any delivery that won't quite fit into the primary purchasers tanks.

 

<div class='quotetop'>QUOTE(N_IL_Priusfan @ Aug 10 2007, 01:14 PM) [snapback]493695[/snapback]</div>

Thanks for bringing this issue up. What price we pay shouldn't be the compelling factor in everything we buy. And cretainly not for something like gasoline!

Take this idea you've brought up and expand it to the world scale. And I'd just like to ask that anyone who possible can, avoid using ANY GASOLINE. I get my water from the same place everybody else does, and I breathe the same air that everybody else does. And I kind of like drinking and breathing and recreating as well!

All this talk of saving 4c... The rare times that I do buy gasoline, I buy it at the most expensive place I can find. The last thing we want is cheap gas, so I do my tiny party to remove some of the low-price competition.

 

<div class='quotetop'>QUOTE(darelldd @ Aug 17 2007, 12:31 PM) [snapback]497878[/snapback]</div>

True, but I still haven't seen any good suggestions for a green accelerant for arsonists. Gasoline is well established, widely available, and all of the dogs are trained for sniffing it.

Tom

 

<div class='quotetop'>QUOTE(Winston @ Aug 17 2007, 12:01 PM) [snapback]497851[/snapback]</div>

Thanks for the input. You're right, there are numerous variables at play that can make comparison difficult, but I generally take the same routes and go to the same places during the day/week and the drop in MPG was immediate and continuous. I didn't have the problem until I tried the Shell gas (which is on the "top tier" list). -I also don't have a Quick Trip gas station anywhere near me; the only gas stations near me are Speedway, Sunoco (which is usually around 60 cents + than anyone else), BP, Moto Mart, Mickey Mart, Swifty (who have often gotten in trouble for having water in their fuel) and Marathon (which has STP additives).

 

My answer is: it depends on what you consider "best gas."

<div class='quotetop'>QUOTE(darelldd @ Aug 17 2007, 11:31 AM) [snapback]497878[/snapback]</div>

I'm glad I'm not the only one disturbed by the talk of hunting down cheaper gas. I buy my gas based on several factors, but price is NOT one of them. Human rights grievances, environmental destruction, and corporate responsibility should all be factors, but price? Fifty cents extra for each tank (even a dollar, if you believe that the gas will perform better) is a small price to pay to make sure that humans are treated like humans and that oil companies are forced to do a little better by the lands they rape to exploit the crude.

Anyone who proclaims to be driving the Prius to better the world's future should be thinking about the other factors involved in the world's future when making their purchasing decisions.

http://www.betterworldhandbook.com/gasoline.html

Although BP makes the grade on this site, it looks as if it reached its greener status because of a lack of some information on some of the other companies. I still prefer Valero/Shamrock over BP because it has no "black marks", but will buy BP over Shell/Exxon/Mobil, etc. in a heartbeat.

 

<div class='quotetop'>QUOTE(doyourealize @ Aug 18 2007, 08:59 AM) [snapback]498296[/snapback]</div>

Wow. Unfortunately after checking their web site there are NO Sunoco stations within 50 miles of my house!!

Anyone know where Speedway fits in? Or who owns it?

 

<div class='quotetop'>QUOTE(N_IL_Priusfan @ Aug 18 2007, 09:12 AM) [snapback]498302[/snapback]</div>

I think Sunoco is a "regional" station, along with a couple of others in that chart. I simply looked at all the stations available to me on a regular basis, then read the information about each, and added some of my own research to come to my decision. I think the consciousness, the actual awareness, of where our stuff comes from that is so important, and therefore will lead to a better world. It's a big reason I don't visit the corner of our highway that houses Wal-Mart & Shell.

<div class='quotetop'>QUOTE(N_IL_Priusfan @ Aug 18 2007, 09:12 AM) [snapback]498302[/snapback]</div>

And after Googling, it appears as though Marathon owns Speedway. hope this helps!