For what it's worth: my Belgian, European experience.
Also here a lot of stories about 'big' differences in fuel economy between cheap and expensive, brand X an brand Y....
But me, who keeps detailed logs of fuel consumption never ever noticed any difference in fuel economy. Every difference seen between 2 fill ups could always be easily explained.
If there's a difference between fuelbrands: it must be so small I'm unable to measure it in daily car and motorcycle use.
Right now at this moment I'm driving around with the most nameless, cheap fuel I ever tanked in my whole life (I vary a lot in the places where I fill up). It's emptied now for >80% and according to my dashreading it's even a bit more economical than previous fill... But I don't want to conclude anything from that because compared with previous fill: far less snow, bit higher temps, bit more highway....
Engine runs fine on it. No problem at all.
I think the wariness towards cheap, off brand gas is do to what actions they take to keep the price low. Perhaps they don't keep as close an eye on their tanks as they should, which leads to more water in the gas.
I think we are talking about two separate issues here.
One is the variation between brands of the quality of the initial product and the second is the point of quality of storage and distribution and sometimes resale practices.
Personally I have always used either Shell or BP for both LPG and unleaded fuel.
The local Shell station is smaller but family owned and the quality of the product is as good as anywhere else. Their station is usually cleaner and tidier than elsewhere too so I give them my money. Actually I drive past the BP to go there.
As to the actual product I have found no difference between Shel and BP although for some reason my car runs less well on Mobil for LPG and fuel and Mobil and Caltex for LPG.
No idea why but there is a measurable difference - around 5%.
The last time I checked this I asked someone else to fill my car (I paid for it) and not tell which brand was in the tank. They reset the car computer to Zero and we repeated the experiment over three tanks (about 1800 klms) and there WAS a distinct difference in the milage even though it was not detectable by me doing the driving.
Before I cared about FE, I drove a showroom clean '66 Skylark, and drove the same route every day, at the same time. I got such a shorter distance out of tanks of gas from a place called "AM-PM" that I reluctantly quit going there. It was the cheapest gas, but when I started paying attention, I realized that I was paying less for the more expensive gas, because I went so much futher.
Here's what I read about it;
The phrase "Bottom of the Barrel" applies. The gas companies with more integrity buy gas from the top of the storage barrel, (where it is more pure) at the refinery, or transfer station, while the cheaper places buy it from the bottom, where there is heavier contaminants, including water. Then they add their respective detergents, etc. and take it to the stations.
I don't remember where I read it, and it may be wrong, or not apply anymore.
All I know for sure, is that the Shell station didn't have the delicious soft-servr Ice Cream, and it was a tough decision.
in central florida there is not a great deal of price difference in regard to "top tier" vs "cheap" fuel. the $2 savings per fill-up is not worth the chance to me. i used to buy cheap gas, and it gave me issues.
besides, a cleaner maintained fuel system AND more yield in mileage is likely. and i use gas cards w/ 5% cash back to boot.
on a side note, i really thought chevron gave me my best(longest) tanks before the 2 near me closed down.
here in oregon it seems so. i'm currently trying out shell gas (it has nitrate additives or some such?) and seeing if this whole business of reducing deposits is worth anything. the last tank (after several arco fill ups) got a really bad milage, even for winter driving, so i'm trying higher detergent gasolines like shell. so far the tank needle hasn't moved much so i'm hopeful it'sdoing something.
Obviously this is so. But within octane groups have we proved that one brand beats the others?
I live in Canada so our Gas options (locally) are:
Real Canadian Superstore
Canadian Tire Fill Up
I've heard lots of bad info from dirty gas in Esso and Petro Canada. As well it seems many folks give the thumbs up for Shell and Chevron.
Any FE differnces noted by those here?
(I'm sure there is a thread for this somewhere already here but I couldn't find it)
Esso is Exxon Mobil
I've had problems with Mobil Gas in New England, especially when its wet out.
Exxon sucks anyhow, don't buy from them if you can help it. They have done big time lobbying against good mileage standards, and have helped to fund the overthrow of Venezuela..(look it up)
Since 3 years ago I switched to Shell all the time, They have that nitrogen in it that is supposed cleanse your engine, so for the sake of constant good mileage I stick with that, I try to use Sunoco other wise cause its promoted by Nascar, so I figure it can't be crap. Even though the gas stations are run down shindigs.
also I think that Mobil gas does not last long. My friend let his car sit a bunch of different times with Mobil gas for months at a time, and the car bucks until he burns it all off and refills it at Shell like I tell him to.
This may have to do with the fact that Mobil gas stations are all old and outdated and allow more vapor into their gas than all these new Shell stations everywhere
I'm still convinced that the content of Shell gas is probably better than Mobil regardless of this, I also think that Mobil 1 motor oil is not that great, overpriced.
But I like Mobil 1 atf. My reasoning is that the super pure synthetic atf they sell works well under the conditions that a transmission operates under, However when you put that Mobil 1 regular synthetic or extended performance the motor runs sort of rough because the oil is so thin and has no substance to it, Unlike Penzoil Synthetic which has some gook to it which my car has personally responded well to, also it being so thin, it squeezes through engine seals easier or something, because my experience was my car used a ton of it, 2.5 liters per oil change, wheras 1.7liters maybe with penzoil synthetic..
Plus Penzoil is Quaker State, They are old school motor oil producers and know what they're doing, Pennsylvania winters are challenging for cars and they know what it takes, is the way I look at it.