Just an observation. When I use gasolines listed as being 'Top Tier' gas, the mileage goes DOWN in my Supra, Scion tC and a Chrysler LHS I had a year ago.
I usually use Gulf oil ,since they are local and usually less $$$ than the others in my area. I have always gotten decent MPG with Gulf.
The last two fill ups I did were with Citgo (Yeah, Hugo...) and the mileage I just calculated from the Scion was 33.56 MPG, the best I have done yet.
With Shell, my MPG usually goes *DOWN* one or two MPG...
Citgo = Commie gas.
It works...
If you are just caluclating single tank averages, I suspect you results are not meaningful. I doubt if the feed stock to the Citgo, Shell, and Gulf sations are actually coming from individual Citgo, Shell, and Gulf refineries. It may be that one or the other uses ethanol, while the other does not. I've never really been able to detect any consistent difference in fuel economy based on brand. In I have bought gas from certain stations on a regular basis, and then becasue of a change in pricing or credit card rebates, switched to another brand. Looking over the data shows little consistent difference between brands, I can show a definite variation based on the month. And interestingly, the worst months are in the spring. My best gas mileage is in the summer months. This may be related to changes in formulation related to the season.
Gulf has an interesting map on their web site that shows thre distribution network and whether they are selling "Gulf" gas or gas from another supplier. They have four categories - Proprietary, Purchase, Exchange, and Throughput. I am guessing these mean - Proprietary: gas that meets some "special" Gulf standards and is delivered directly by Gulf; Purchase: gas purchased for cash from another supplier as is, but sold as Gulf; Exchange: gas aquired from another supplier by exchaning production as is but sold as Gulf; and Throughput: Gulf gas moved through another system (see
Ed
My understanding is the top tier gas just refers to additives which may help keep the engine cleaner. There would be no impact on mpg which would probably be most affected by ethanol content as you mentioned.
Other than the impact of a clean fuel and combustion system vs. a dirty fuel and combustion system.
Dirty injectors, dirty valves, etc--all that will cause lower mileage. Keep everything clean, get better mileage.
Anybody know how additives are put in the truck tankers? A fellow in another group says a number of gas companies all get their gas from the same Hess depot near his home, all the gas coming through the same pipeline from the same ship. Says it's all the same gas going to Texaco, Chevron, etc, and the additive claims are BS. The only answer I can think of is they put the additives in at the Hess depot, but I don't know. .
--Vic
In most places all the gas stations in that locale get their gas from the same terminal. Additives are added when the tanker trucks that deliver to the retail stations are filled.
Here is an article that describes the process
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With the state of American Industry today, I would be surprised if the different brands still customize their additive packages. In my part of Ohio, gas stations buy their gas from either Sunoco or BP's refinery. I would guess that Sunoco blends their gas for their stations and anyone buying gas from their refinery is really getting Sunoco gas. I do know that only one firm hauls gas from both refineries. So if the refinery still sells a base stock and each brand then adds it's own additives, someone has to stock those additives. Either the refinery, the trucking firm or the gas station would stock them and I can't see Sunoco stocking additives for Gulf or Shell.
Jack
Thanks.
--Vic
You are very hard-pressed to measure to the nearest tenth of an mpg.
You will not be able to measure to a /hundredth/ of an mpg unless maybe your tire radius varies no more than say a thousandth of an inch, for instance.
Be satisfied if you can measure to the nearest whole mpg. Plenty of people will tell you that EPA can't even do that.
Several oil companies still advertise a custom additive package, so they would have to do it everywhere to not get nailed by the Gov't.
The pipeline company owned tank farm that all the delivery tank trucks in the region fill from would stock the various 'special' detergent packages and meter them into the pipeline commodity raw gasoline as the trucks were filled from the metering racks.
If the gas is going to an independent gas station or a corporate/ government private fueling station, they just put in a generic package that meets the federal minimums - unless the customer pays extra for a double dose or something better...
The detergent is probably shipped in by the 55-gallon drum or the
300-gallon or 600-gallon UN Cube style tank, ultra concentrated. An educated guess says they only need a pint to quart of detergent to treat a full 8,000 gallon tank-truck load, so one trailer load of detergent would go a long way.-->--
Let alone hundredth. 33.56? That's a bogus and meaningless number.
Unless he starts with a steam-cleaned and empty tank, and does nothing but fill it from known cans with known quantities of fuel in it, he's lucky to know within one or two mpg what the real number is.
Ed Zachary.
It's important to know when you normally hover around 33mpg that all of a sudden you're hovering around 28mpg, but moving around anywhere from
32 to 34, centering around 33 on a regular basis? That's temperature, tire pressure, tire wear, and gas pump shutoff valve variability talking. Nothing in the engine has necessarily changed.
From that article:
That one refinery may create the base gasoline that's used for many brands, that refinery offers its customers a Chinese menu of choices for filtering and anti-contamination, as well as additives.
To say "it all came from the same refinery, therefore it's all the same gas" is like hearing my chemistry-challenged father exclaim "it's just salt!" when someone told him that making aspirin involves "salt of salicylic acid".
Two tankfuls does not make a very good trial. In order to compute variance of a measurement you should take about ten, and compare the resulting variance to the differences between milage with different gases. A difference less than the variance is meaningless. Fortunately, many calculators these days will compute variance as well as average, so the statistics are a lot easier these days.
Your engine needs some work. I always get from 33.62 to 33.68. It once dropped to 33.34, but I took it to the dealer for a tune-up, new plugs, filters, the works, and it immediately went up to 33.65. It was $550 well spent!
$550.00?
Yes, I had a discount coupon
Edwin Pawlowski wrote: (Re 33.56 MPG Scion)
Your engine needs some work. I always get from 33.62 to 33.68. It once dropped to 33.34, but I took it to the dealer for a tune-up, new plugs, filters, the works, and it immediately went up to 33.65. It was $550 well spent! ______________________________________________________
"Matt" wrote:
$550.00? _______________________________________________________
Whooooooooooosh!
And the temperature volume compensation thingy on the gas pumps here in Ontario.
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