I usually go with mid-grade gas and I get about 300-320 mpg per tank. I had a .65 discount at my usual gas station and decided to give the high test a try. I have lost major milage with this tank, I am at 230 miles with this tank and in need of a fill up. I know, I know... I should have been using high test the whole time. But what could cause this rather dramatic loss of milage? I have no codes showing and none come up when I scanned. The plugs and filter are within replacement intervals as are all fluids. I checked the oil for the "chocolate milk" color that would indicate coolant in the oil. I have noticed no changes in start-up or the way it runs hot or cold. There is the normal cold weather condensation at the tail pipe and it does not smell or have the color of coolant (clear). All four 02s have been changed within the past year (all at once). Could be the whatever measures the fuel level?? Just bad gas?? The only thing I have not changed is the wires but this truck started consuming more fuel the instant the high octane was in the tank. I fill up at a local grocery chain but I have never experienced anything like this!!!

 

I usually get right about 220-230 before my gas light comes on. If i can get a tail-wind on the highway I can maybe get 300 to a fill-up. I've never tried 89 octane though, mine's gotten 93 octane with only Shell or Pilot gas since i bought it.

 

Ok, well after seeing Bamaboy's post I literally ran out to make use my odometer was set to miles and not kilometers. It is to my relief set to miles, I was going to be very embarrassed.

 

what is "mid-grade gas?
i use 93 oct.
religiously on all my cars,
to narrow it down i only use shell.
BP, or Exxon in emergency.

what have you been using before and what did you use when the mileage dropped?

 

Seriously?

 

actually its possible you have more ethanol in the gas then usual. We usually see a few stations causing havoc on the new ones by dumping in too much ethanol than it says on the sticker.

 

May be an obvious question but were your driving habits the same? For instance, miles on the freeway vs. miles around town?

I think what yesmar was asking was what octane grade is your "mid-grade", it can be different depending on where you live.

I'm sure you'll catch a lashing from others for not running premium like you're supposed to

 

different stations and states have different octane ratings for each level, a mid in one state may be the same as high in another thats all he was asking. but to answer you question the high grade may not be used at your station as much meaning its been sitting longer and is old. If I have to get gas at a "discount" station I always get the low cause noone gets premium there and good 87 is better than old bad premium.

 

2X ON THE ETHANOL !!!!!!!!!!
I live close to the canadian border and we have a local station which buys it's fuel from across the border and has no ethanol in it, the pump says its only 87 octane......but my truck gets better mileage and runs better on it than any "premium" fuel I get anywhere else with ethanol. I too get ~~ 325 / tank......I get a little scared using a 87 grade but I've never heard the engine knock under accelleration......I throw a little octane boost at it every once in a while though

 

Wow, I have a 98 Disco 1 with 146,000 miles. I have a 3" lift and 33" tires. I use regular and I might get 150 miles per fill. I use mine for bbumping around town and off-roading, so I don't expect to get much, but I would be excited if I got 230 or 300 per fill.