Ok, so my friend and I were having a debate this weekend regarding different gas brands (i.e. Shell, Chevron, Exxon/Mobil, etc.)

She's convinced that different brands yield different gas mileage on her vehicle... up to 10-20%!!!

I disagreed... but neither of us had Hard Data to show for it. I find it hard to believe that one brand could yield up to 20% different gas mileage from another.

So that leads to my question: Does anyone out here experience different gas mileage from different brands? And please share which you think is the best.

I typically use Exxon/Mobil on my Disco 2 and get between 13-16mpg, depending on my commute.

 

 

Octane ratings are just that. Doesn't matter if it's Shell, Sunoco, Hess etc. The will all give the same exact result. It is a federal law (with state variances)believe it or not.

The I-Net is your friend, do a bit of searching and you'll find all the info you want.

Your lady friend needs a refresher course in math 101 ;-)

 

This must have been the topic for the week…similar type of discussion over the weekend.

As I understand it (and I welcome correction); High Octane ratings do not indicate a more powerful fuel. Octane actually slows down the fuel burn rate. Because the burn rate is slower, the action is smoother throughout the burn cycle; thus producing a more complete power stroke / combustion in the cylinders.

From WIKI: The octane rating is a measure of the autoignition resistance of gasoline (petrol) and other fuels used in spark-ignition internal combustion engines. It is a measure of anti-detonation of a gasoline or fuel.
Octane number is the number which gives the percentage, by volume, of iso-octane in a mixture of iso-octane and normal heptane, that would have the same anti-knocking capacity as the fuel which is under consideration. For example, gasoline with the same knocking characteristics as a mixture of 90% iso-octane and 10% heptane would have an octane rating of 90. [1]
http://en.wikipedia.org/wiki/Octane_rating

MWmG

I believe the comparison from brand to brand is in the Fuel Additives.

 

Additive packages and also Ethanol content. Ethanol can drop your MPG by 10% and the fuel is still the same 91 octane.. Almost everyone around my parts has Ethanol and it sucks. Gas prices are about the same now with or without it and it is hard to find someone that doesn't have it and carries premium.

 

We also have Super Tuesday. Save $.06 per G. on premium.
My truck also runsbest on Shell or BP. Both 93 octane. Speedway is 91 and Marathon 92 and Mobil 93.
I agree that it is the addatives. A clean engine is a happy engine.

 

Heres my opinion, since switching to JUST shell gas I have noticed quite a difference. Its said to be the cleanest gas on the market, shell also adds additives to it that reduced engine gunk. I also noticed about a 1.5 MPG increase with it as well. I always use shell premium because I fell in the long run it will be a benefit. But in my area Shell gas tends to be about 3-5 cents more, but i can deal with that.

 

15% ethanol DOES make a difference, the VERY old tech that the disco engine runs on was designed for true, full petrol fuel. adding ethanol does nothing more than hurt gas mileage, make the engine run hotter, and make the product cheaper for the purveyor (and slightly reduce emissions [which I think could also throw off the ECU's calculations, hence hurting MPG])

 

I too have fallen in love with Shell... I have ALWAYS been a shell fan!.. even though it is about 10 cents more expensive!... I believe that Chevron is starting to get up to the Shell status, if I'm not mistaken, so we'll see!!

 

Shell has always given me about 5% better fuel economy in all of my cars in both 87 and 93 octane rating, so it probably does mean the additives make the difference.