Sudden loss of 2-3 MPG?

Gamester · Dec 30, 2016

So I usually can get around 17-18 MPG in my supercharged hemi. However, for some reason a few weeks back when we had our first really cold below 0 day, I suddenly now only get 15MPG. The temperature has since warmed up and it is still only getting 15MPG consistently. I'm at about 19,000 miles right now and haven't had any issues and there is no noticeable loss in power or anything so I'm not sure why it dropped. Any thoughts?

stimpy433 · Dec 30, 2016

Winter blend gas, I know I always lose some MPG once they start selling it. My MPG goes back to normal once the summer blend gas comes back.

huntergreen · Dec 30, 2016

different gas from a different fill station?

Gamester · Dec 30, 2016

Same gas station I always use, but I wasn't aware there was any change in fuel during the winter months; maybe it is something like that.

huntergreen · Dec 30, 2016

dont know where you are, but in nj, the change to winter formula occurs sometime in october.

SyN · Dec 30, 2016

I agree with stimpy! I wouldn't concern yourself too much with it. Yes it does SUK but there really is nothing you can do to change it.
I don't think there are any fuel additives to help boost the mpg even in the slightest.

Just drive as civilized as you can.

Gamester · Dec 30, 2016

SyN said:
Just drive as civilized as you can.

Lol, I wouldn't have a supercharger if that was a possibility :Big Laugh:

Yea I guess I will give it a month or two and see if it gets better or not. If I start seeing changes in performance I will look further into it at that point.

Thanks

Johnnymac2k6 · Dec 30, 2016

huntergreen said:
dont know where you are, but in nj, the change to winter formula occurs sometime in october.

this is correct, and this is why your mileage went down. period. I easily lose 1-3 MPG during winter months. winter blend gas, plus more dense cold air with longer warm up periods for the engine, so a richer running engine, etc.

1SilverBullet2 · Dec 30, 2016

I agree it's just the winter blends. I'm down about 3-4 mpg with my truck because of the gas and idle time.

Sent from my iPhone using Tapatalk

Gamester · Dec 30, 2016

I didn't think the idle time was factored into the MPG gauge, but if so that would certainly explain it alone since on really cold days I usually do 10 min of warm up time at home and work as well.

Thanks guys

SyN · Dec 30, 2016

I personally during the summer months try never to let my 5.7L idle for more then 2 min.

Winter months 4 min is tops. Then attempt to drive slow for at least 5 blocks to let the trans/Rearend oil turning enough to get every moving part proper lubrication.
Just not a huge idle fan since this is where most fuel dilution occurs as well as lowest Oil psi.

Blackout15 · Dec 31, 2016

You might want to check your tire pressure too, I know I lost a few lbs. in all 4 corners when we got our first cold spell. It may not be much but it doesn't help MPG at all. Also as stated winter blend gas isn't helping at all either.

novelmike · Jan 1, 2017

I've watched my MPG gauge move while I'm siting in my truck at work. I'm either waiting with the a/c or heater on, depending on what time of year it is. So idle time is most definitely factored in.

MEchase · Jan 1, 2017

Does everybody get winter blends or is this something usually reserved for colder/northern areas?

Hootbro · Jan 1, 2017

MEchase said:
Does everybody get winter blends or is this something usually reserved for colder/northern areas?

My understanding is everybody eventually gets it but some colder regions will get the winter blend sooner.

Sir John · Jan 2, 2017

Hootbro said:
My understanding is everybody eventually gets it but some colder regions will get the winter blend sooner.

In Western NY we get the winter blend sometime in October and it switches back to summer blend sometime around May.

gofishn · Jan 2, 2017

Regarding Winter fuel blend:
Everyone eventually gets it, simply put, there are not that many different pipelines pumping gas, from the refineries, all across America.

As regards the OP mileage, it's the Thanksgiving and Christmas dinners.
You just ate too much, the truck is now hauling much more of a load and your gas mileage went down.

Lay off the Brach's Chocolate covered cherries.
... and get to the gym. Your overworking that Hemi.

Gamester · Jan 3, 2017

or maybe it's from the weight of the extra muscle gained from the gym; ever thing of that? :naughty:

Rado · Jan 3, 2017

I agree with Winter Gas causing the drop.. It happens every winter for me in Maine

gofishn · Jan 3, 2017

Gamester said:
or maybe it's from the weight of the extra muscle gained from the gym; ever thing of that?

Nope. I can honestly state I would have never thought of the Gym.
Not for the last 30+ years.

Sudden loss of 2-3 MPG?

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