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My fuel mileage has dropped. Why?????

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My fuel mileage has dropped. Why?????

Old 04-06-2007, 09:02 AM
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Default My fuel mileage has dropped. Why?????

Once again, I'm requesting the vast knowledge of the tht audience.

Last week, I had my oil changed. Before the oil change, the electronic mpg thingy on my '03 Expedition put me averaging 13.9 mpg. When I calculated the mileage at fill ups, it was always spot on. After the oil change, it's been steadily dropping. This morning, I was down to 12.4 mpg. I haven't calculated it at fill up since then, but I tend to believe the display.

What could be happening to drop my mileage 1.5 mpg? Could it be something that happened at the oil change? I haven't changed my driving habits since then. I'm at a loss. Any ideas?
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Old 04-06-2007, 09:09 AM
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Default Re: My fuel mileage has dropped. Why?????

That is definately one of the great things about 'flowmeters' of any kind.. Sends an alert for ya, something is awry..
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Old 04-06-2007, 09:23 AM
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Default Re: My fuel mileage has dropped. Why?????

e10 gasoline...... all fuel mileage has dropped with it
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Old 04-06-2007, 09:26 AM
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Default Re: My fuel mileage has dropped. Why?????

Check your O2 sensor.
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Old 04-06-2007, 09:35 AM
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Default Re: My fuel mileage has dropped. Why?????

running your air conditioner now??
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Old 04-06-2007, 10:05 AM
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Default Re: My fuel mileage has dropped. Why?????

12? Ouch.

I'd say A/C as well.
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Old 04-06-2007, 10:13 AM
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Default Re: My fuel mileage has dropped. Why?????

Check your oil level and weight...if it's too full, you would suffer in the MPG department.
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Old 04-06-2007, 10:17 AM
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Default Re: My fuel mileage has dropped. Why?????

Not the A/C. We averaged the same 13.9 last summer at 100+ deg.

With the O2 sensor, could it have gotten screwed up during the oil change?

I'll check the oil level right now.
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Old 04-06-2007, 10:21 AM
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Default Re: My fuel mileage has dropped. Why?????

Just checked the oil level. The dipstick is showing about and inch over max fill. Could this be it?
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Old 04-06-2007, 10:23 AM
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Default Re: My fuel mileage has dropped. Why?????

Neck, I noticed a change in the mileage of my F-150 if the oil is not correct.
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Old 04-06-2007, 11:11 AM
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Default Re: My fuel mileage has dropped. Why?????

If the crankshaft is hitting the oil it would show up in lower MPG AND it would put stress on your engine! Heavier wt oil can decrease MPG as well. I would drain enough oil to bring it down to the middle mark of the dipstick and recheck the MPG. It's not uncommon to overfill or underfill during an oil change. My sons car holds approx. 5 qts and on the last oil change they only put in a little more than 2...car ran a little hotter than normal, but suffered no damage before we discovered the problem.
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Old 04-06-2007, 11:35 AM
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Default Re: My fuel mileage has dropped. Why?????

diesel or gas?? change the air filter....
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Old 04-06-2007, 11:45 AM
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Default Re: My fuel mileage has dropped. Why?????

tire presure / air filter / gas grade / so many things can add up fast and hurt your mpg. I been living with 410 gears in my 04 GMC 2500 fwd I feel your pain
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Old 04-06-2007, 11:47 AM
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Default Re: My fuel mileage has dropped. Why?????

You may want to change brands of fuel. You nornal fuel guy maybe has switch his supplier
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Old 04-06-2007, 12:05 PM
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Default Re: My fuel mileage has dropped. Why?????

neckbone - 4/6/2007 9:21 AM

Just checked the oil level. The dipstick is showing about and inch over max fill. Could this be it?
Yes, wipe stick and check again . If its still there drain the extra quart out.

you did change filters ?
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Old 04-06-2007, 11:19 PM
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Default Re: My fuel mileage has dropped. Why?????

I agree with B-Faithful, It's the e-10.
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Old 04-07-2007, 06:01 AM
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Default Re: My fuel mileage has dropped. Why?????

"Just checked the oil level. The dipstick is showing about and inch over max fill. Could this be it?"

Yep. That's it.
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Old 04-07-2007, 07:40 AM
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Default Re: My fuel mileage has dropped. Why?????

Ethanol Blended Gas = Lower Mileage?

According to a recent article, drivers in Honolulu (and perhaps elsewhere) are complaining of reduced gas mileage in the two months since Hawaii switch to gasoline blended with 10% ethanol. According to the Ethanol Promotion and Information council, most drivers using a 10% ethanol-blended gas will experience a 1-2% drop in mileage. But some drivers in Hawaii are claiming that their mileage has dropped by 25-30%. While I’ve heard of substantially lower mileage in cars running on E85 (a blend of 85% ethanol and 15% gasoline that can be used in certain makes/models) I never really heard anything about reduced mileage in the more ’standard’ 90/10 ethanol blend.
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Old 04-07-2007, 08:20 AM
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Default Re: My fuel mileage has dropped. Why?????

I see that there were a few responses that blamed the A/C....But,

While I remember A/C sucking MPG's years ago, I have to admit that it really doesn't affedt my MPG's now......

Maybe newer technology??

Anyone else notice this?
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Old 04-07-2007, 12:01 PM
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Default Re: My fuel mileage has dropped. Why?????

sixpack324 - 4/7/2007 8:20 AM

I see that there were a few responses that blamed the A/C....But,

While I remember A/C sucking MPG's years ago, I have to admit that it really doesn't affedt my MPG's now......

Maybe newer technology??

Anyone else notice this?
well at 12 mpg..would you notice if it did?
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