Winter Fuel Economy - PowerStrokeNation : Ford Powerstroke Diesel Forum
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post #1 of 11 (permalink) Old 12-08-2011, 10:10 PM Thread Starter
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Winter Fuel Economy

I live in Indiana and I don’t think they sell much in the way of winter blend here. I’ve had tanks gel up (“cloud” is the ASTM term) at 7 below here. Maybe at big truck stops up along the Indiana Toll road that serve trucks that may go farther north, but few other places here.

As for the heat content of winter blend, it is proportional to the No. 1 content. The heat value of straight No. 2 is 139,000 BTU/gal. For No. 1 the heat content is 130,000 BTU/gal. So if you winter blend were the outstanding stuff you get in Nebraska and the Dakotas (66% No.1) you get a heating value of 135,900 Btu/gal or about 2% lower heating value.

Most stations that sell real winter blend are quite proud of it (it sells at a considerable premium) so if you have to ask, it probably isn’t winter blend.

Now the decrease in MPG is very real, but I’d ascribe the reduction mostly to increased aero drag.

Remember the part of the road load equation that deals with aero drag.

HPaero = kρCdAV3 where
K is the consolidated conversion constant
p is air density
Cd is coefficient of drag
A is frontal area
V is velocity
From standard psychrometric tables we see that:
At 0°F ρ=603.7 grains/ft3
At 70°F ρ=520.0 grains/ft3

We see that when air temperature drops from 70 to 0 the air density increases by 16.1% and thus the biggest component of road load goes up by the same amount.

Winter blend MPG loss = 2%
Denser air MPG loss = 16%

Winter has other effects that I cannot quantify.
a. Increased rolling resistance from snowy/slushy road surfaces
b. Driving conditions (including other drivers) make hypermiling difficult

2000 F-350 SC 4x2 6 speed
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post #2 of 11 (permalink) Old 01-13-2012, 01:25 PM
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Re: Winter Fuel Economy

mine seems to have dropped to around 16.5 and I dont drive like i stole it. I seems to help when I plug mine up at night. I'm guessing being plugged up gets it to operating temp. faster for a more complete burn.

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post #3 of 11 (permalink) Old 01-13-2012, 05:27 PM
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Re: Winter Fuel Economy

I'd also say people see worse mileage b/c of longer warm up times and letting the trucks idle longer to keep them warm. Guys don't shut them off as much probably in the winter time.

2000 F-250 ext cab 4x4 6 spd. Glowshift gauges(egt, boost, and fuel pressure), PHP tuned, DIY intake. MBRP 5 inch straight exhaust with 6 inch tip
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post #4 of 11 (permalink) Old 01-23-2012, 02:08 AM
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Re: Winter Fuel Economy

Warm up time always hurts mileage in the winter. If you are getting a true blended fuel with #1 in it you are usually gonna lose economy and power. We keep our pumps at 50/50 blend. You don't have to worry about gelling up but it does cost more. Right now 1 is around 15 cents a gallon higher here than 2. But 2 will turn to snot at around 10 degrees. All the other stations in town are straight summer fuel with additive. Needless to say a month ago we saw a lot of pickups get pulled to our station on log chains to our straight #1 pump so they could get blended down and get ungelled. They gripe at us because our fuel costs more until it gets cold and then it pays off. lol I know the drivers that haul the fuel into the other stations. They tell you it is blended but I know for a fact that it isn't the guys who haul it tell me that it isn't.

Clayton


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1995 F-350 Crew Cab 4x4
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post #5 of 11 (permalink) Old 01-23-2012, 03:23 AM Thread Starter
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Re: Winter Fuel Economy

Some of the best winter blend I ever saw was out on the Great Plains. It does get REALLY cold there, like 25 below.

Same with Alaska.

Few other places go more than 25% No.1.

You ever bothered to think how dense air is at 25 below and under 4000 ft altitude? Aero drag is propotional to air density.

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post #6 of 11 (permalink) Old 04-12-2012, 08:20 PM
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Re: Winter Fuel Economy

Interesting stuff.

This past winter I changed work locations for a few weeks at a time (one 10 minutes from home all back roads, one 45 minutes from home mostly highway) and noticed my mileage stayed relatively the same between the two drives (low 15s)? Maybe the increase air density resistance of the highway trip equaled the impact of the limited warm up of the short trip?

I am starting to see a difference between the 2 trips now that it's warmed up a bit. The shorter trip is around 16mpg and the longer trip is around 17mpg.

Robert

2003 F350SD 7.3L CCSB
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post #7 of 11 (permalink) Old 10-13-2012, 03:22 PM
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Re: Winter Fuel Economy

you stop to think its not so much the cold dense air as, the cold thick lubricant inside the motor, and every bearing. try starting an engine at -30 with the same oil as summer. it turns way slower, and I will put any money on it, that it is not because the air in the cylinders is colder and denser. even the engine oil which is much more exposed to heat than say a wheel bearing or transmission, take 3-4 times as long as the coolant to reach full temp. when the grease in a wheel bearing is like molasses, it takes far more Hp to make it turn. typically I figure on a minimum of 30 minutes of 60+ mph continuous driving before everything turns as freely as in summer.

year ago I saw a "Power up" grease( standard #2 grease) demonstration, it actually reached best lubricity as it was beginning to smoke. point is what do you think its friction is when its almost as hard as candle wax


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post #8 of 11 (permalink) Old 10-13-2012, 03:43 PM
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Re: Winter Fuel Economy

Quote:
Originally Posted by nitrogen View Post
you stop to think its not so much the cold dense air as, the cold thick lubricant inside the motor, and every bearing. try starting an engine at -30 with the same oil as summer. it turns way slower, and I will put any money on it, that it is not because the air in the cylinders is colder and denser. even the engine oil which is much more exposed to heat than say a wheel bearing or transmission, take 3-4 times as long as the coolant to reach full temp. when the grease in a wheel bearing is like molasses, it takes far more Hp to make it turn. typically I figure on a minimum of 30 minutes of 60+ mph continuous driving before everything turns as freely as in summer.

year ago I saw a "Power up" grease( standard #2 grease) demonstration, it actually reached best lubricity as it was beginning to smoke. point is what do you think its friction is when its almost as hard as candle wax

If it takes that long for your truck to warm up, something is wrong with it.

Mine is up to temp in 10 minutes. I usually give it 2-3 minutes to idle when it's below freezing, then drive her lightly (Below 2,000rpms) until she's up to temp. Coolant and oil are usually up to normal temp (as well as tranny) at 10 minutes, maybe 15 if it was below 0*F out.

BTW...(No directed at Nitrogen) if you live in an area that sees freezing (actual, not "I'm cold") temps.... run synthetic. Truck will start easier, run better, and be better protected. Plus save wear/tear on your batteries/starter.

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post #9 of 11 (permalink) Old 10-13-2012, 04:00 PM
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Re: Winter Fuel Economy

when I said everything i was referring to engine oil, and gear lube and grease. my coolant is up to 195 in about 10 miles. that is basing my oil temps on the torque app on my phone, and my experience in driving highway tractors with real oil temp gauges for 25 years.
i can warm that tractor up to 195 in the yard before I move an inch, and it still takes 10-15 miles of heavy pulling before that oil temp peaks.
yes I have been running synthetic year round for 15-20 years and it helps with cold starting big time. back in the day i hooked up to a semi trailer fully loaded at minus 35. normal cruise speed was 73 mph, it took me 30 miles of highway to get it over 55 running flat to the floor the whole time. that is how much extra friction cold wheel bearing lube makes. and most semi's actually use gear oil not grease in the bearing just for lower friction.
one thing that so many people just really do not comprehend is the friction in all the components besides the engine, really contributes to higher rolling resistance. they are the ones that sit and warm up an engine for minutes and hours on end(wasting fuel) and then they still have to warm up all the other lubes by driving, and until they are warm they still roll hard. I'm definitely in the 2 minutes or less of warmup and just drive nice. hey i'm still on the factory headbolts and gaskets on a 130k 6.0 can't be screwing up too badly:) now if I had a newborn, or was taking a tropical pet to the vet in January........then I would make an exception.


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post #10 of 11 (permalink) Old 12-21-2013, 05:12 AM
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Re: Winter Fuel Economy

This is an interesting read. I know my warm up time is slow in the winter, but never really worried about the lubricants other than the engine oil.
My E350 van has the 7.3 PSD and I try not to use it much in the winter weather. my summer fuel economy runs in the 24-25 mpg empty range and 19-20 with the trailer loaded on the back.
winter drops to 14-15 empty, but only drops to high 17s-18mpg loaded.

It uses around 1 litre of 15/40 diesel oil in its 10,000km service interval so its not worn out or anything.

it doesn't get nearly as warm on the guage in the winter unless i'm pulling trailer. so all I really use it for in the winter is hauling. my work commute is only around 22miles round trip so that is a little hard on it in the winter.

we have had some cold nights already and it started pretty normal even after sitting for a couple days.

our coldest nights were in the -20 degrees C range.
mileage is 440,000km and our imperial gallon is 4.54 litre instead of 3.78 litre US gallon.

I was going to do a synthetic oil change for the winter but for its limited winter use I'll just plug it in if it drops under -25 C .


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