I fill up with Mobile or Shell. I heard that those two have the highest quality gas. Last couple of weeks I put Marathon in and I am getting almost 40-50 MPG more. How can this be?? I drive the same, (same old routine school, work, girlfirend ). I know it got wamer here in chicago but, I drove my car in warm weather on Mobile and Shell and never got past 315 MPG. Now im well past 350MPG.

 

You mean MPT, right?

 

Yes sorry MPT
I wish I could do 350 per gallon

 

must mean MPT... anyway, could be additives, could be the amount you put in the tank, could be the marathon gas pump is calibrated to stop at a different point and is putting more gas in your tank (probably this).

 

Yes it could pump more gas, but 50 more GPT thats a lot, I dont think that it pumps more than 2 gallons in. I think I will stick with Marathon for now its about 10c cheaper and from my experience the MPT are much better.

 

The weather is warmer so your cat is reaching operating temp sooner. I'm seeing a 1 mpg better now than last month and I also live in the Chi area. Stick with the high additive stuff.

 

By high additive stuff do u mean Mobil and Shell 93 octane or any 93 gas out there.

 

BP 93 octain usualy gets me around 380 when i use shell or cheveron 93 im lucky to get 310

 

Name brands have higher amounts of detergents to keep the fuel system clean, and it usually increases as the octane rating goes up. That's where the 10 cent a gallon price diff comes in, well some of it.

 

Then how come I get better MPG using the cheaper gas than when I use Mobil or Shell.
I dont know any more, Im starting to think that it dont really matter where u buy your gas from, and the supposedly better gas is actually worse. But thats just my opinion

 

As I said in post #6. It's the weather, go back to Mobil or Shell and if the spring fever doesn't get you, you shoud see the same increase (I have bee driving a lot faster now that the weather is warm).

 

Just to clear this up again. All gas is the same. You have to realize that. It's called fungible for a reason. There are a few pipes in the country and people buy spots on those pipes. The gasoline is exactly the same so what Shell puts in the pipe isn't the same gas as they pull out. The only difference from store to store is the additives. They are in minute amounts and almost every maker uses the same type of formula to reduce deposits, etc. Gas is gas and if you think it isn't, you just got an odd batch but Mobil, Chevron, all the same liquid. My uncle worked as a pipeline operator so I know this

 

Thanx for clerifying this. Now I will buy gas wherever its cheapest

 

are you serious? i fill up with chevron 93 all the time.. and i have yet to get past 320 mpt... i think im gonna have to try bp gas.