Bad Fuel

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RDX Aspec Adv.
I was going to title it something else, but I remember being 12. I also remember being a day younger, yesterday. I've matured!

Anyway, for the last 2 tanks, I've averaged barely 26mpg with my CX5 Turbo. I got fuel again tonight, and BOOM! I am back up to averaging 29-30mpg again. Same station. I wonder if maybe they put the wrong fuel in the tanks? I don't know what that "wrong fuel" would be, as when I used 93 octane in San Antonio, it was not E0, and I didn't notice a drop. Maybe I got 2 tanks of 87 octane?
 
I see no MPG difference between 87 and 93. Did 10 tanks of each and always landed between 28 and 28.5. I'm now permanently on 87.
 
Unless you're driving a GT-R or Signature, using Premium shouldn't really make a difference in MPG.
 
Hey Uno,

Any wild swings in weather? Perhaps the last two weeks were really cold? I've noticed that when the temperature drops to below freezing I significantly lose MPG.
 
I would watch it though. Get a code reader and check for occasional codes. Not all codes trigger the check engine light immediately.

Also could be a slightly engaged e-brake or caliper...slipping tranny...many things.
 
Unless you're driving a GT-R or Signature, using Premium shouldn't really make a difference in MPG.

The CX-5 GT Reserve and Signature only recommends 93, so you can run 87 no problem. That said, you will get better performance and mileage with 93. The question on most people's minds is whether 93 is worth it. You get a slight bump in mileage, but you're also paying more for it.

I have seen a slight mileage increase using 91 in my CX-9 (can't get 93 here). I get an increase of approx. 1.5 mpg. This is what I've personally experienced after filling the tank with Shell 91 for a year, then running Shell 87 for 4-5 months, then going back to Shell 91. I guess it's possible that in your case, Uno, the station goofed and put 87 in the 93 reserve tanks, but I think something else is up because the change in mpgs wouldn't be so abrupt over 2 tanks of 87.
 
Hey Uno,

Any wild swings in weather? Perhaps the last two weeks were really cold? I've noticed that when the temperature drops to below freezing I significantly lose MPG.

Dude, it was colder now than in the last few weeks. I'm truly at a loss. No clue what would cause such a drop and then resurgence in normal mpg.
 
I would watch it though. Get a code reader and check for occasional codes. Not all codes trigger the check engine light immediately.

Also could be a slightly engaged e-brake or caliper...slipping tranny...many things.

But the mpg shot right back up after THAT refill. Super odd.
 
I have seen a slight mileage increase using 91 in my CX-9 (can't get 93 here). I get an increase of approx. 1.5 mpg.

I've had the same bump when comparing 87 and 93, although I can't get my mileage much over 24.
 
Winter vs summer gas? I consistently get a couple MPG less with winter blends. I can only speculate, but maybe that station got a batch of winter fuel followed by the last of the summer blend. If you MPG drops again at the next fill and subsequent fills after Im guessing its a switch to winter blend issue.
 
Winter vs summer gas? I consistently get a couple MPG less with winter blends. I can only speculate, but maybe that station got a batch of winter fuel followed by the last of the summer blend. If you MPG drops again at the next fill and subsequent fills after I*m guessing it*s a switch to winter blend issue.

Yeah my winter MPG sucks compared to the summer, but I think it's more my heavier snow tires than the gas.
 
Winter vs summer gas? I consistently get a couple MPG less with winter blends. I can only speculate, but maybe that station got a batch of winter fuel followed by the last of the summer blend. If you MPG drops again at the next fill and subsequent fills after I*m guessing it*s a switch to winter blend issue.

It indeed has dropped again. Same station.
 
Is this going off the trip computer or tank to tank calculations?

Trip computer. It's very accurate in my T&E of it. More accurate than most pumps error of margin on the "click" unless you fill to overflow or something as a way of consistent measure.
 
dont know how it's in the states but in many places in the world some stations dilute or sell cheap gas that's not in the octane stated.
 
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