MPG decrease in very cold weather??

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28
Location
Alberta
Thread starter
I'm kinda new to driving and was wondering what kind of penalty I can expect in extremely cold weather(-20c sustained)? Drives are typically 15mins or less. I replaced my lower intake manifold gasket and though performance has returned fuel economy has slightly dropped. It's only been a 1/2 tank though and since i did the repair it's been at least -15c every day. I'd like to hear your thoughts or observations on mileage in the cold.
 
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28
Location
Alberta
Thread starter
Originally Posted by JohnnyJohnson
Well how long is it going to take for that engine to warm up and that engine idle to drop below 1800 RPM?
It idles at 800rpm at startup then falls to 700 in about 5 mins and gets to temp by the time I get to work 15mins.
 
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5,442
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MTL, CANADA
How much are you idling? I can ssy my mpg went from 17-18 to 14-15 in winter. All short trips. Granted I am am idling alot more whereas i dont ever idle in spring, summer, or fall...
 
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9,974
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Colorado Springs
Originally Posted by 2009Caraman
I'm kinda new to driving and was wondering what kind of penalty I can expect in extremely cold weather(-20c sustained)? Drives are typically 15mins or less. I replaced my lower intake manifold gasket and though performance has returned fuel economy has slightly dropped. It's only been a 1/2 tank though and since i did the repair it's been at least -15c every day. I'd like to hear your thoughts or observations on mileage in the cold.
What car? What oil is in the car? Is it in garage? Whatever you do, first few km's do not turn on heat and vent for 2-3km's as that delays warming up. Also, do not idle longer than necessary to put seatbelt, get accomodated. Move and move slowly, allowing transmission (assuming it is automatic) to [censored] around 2,000rpms.
 
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1,906
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Canada
At -35C, right after startup, on a car that typically gets 32mpg, the real-time MPG (on flat land) can be as low as 4-5mpg on my car. Early 1990s 3.1L GM V6. Yes, it improves rapidly as things warm up, but on a 15 minute drive, you'll be exposed to a lot of such operation unfortunately. Transmission keeps it in first gear for quite a while. To get it into second when its that cold feels like total abuse the revs required. The transmission doesn't have electronics (all vacuum or oil driven), so just the sheer viscosity of the fluid causes that behavior. BTW, welcome to the forums! Glad to see another fellow Canadian here.
 
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Maricopa Arizona
If you could get the drivetrain up to operating temperature quicker it would help with your fuel economy but being cold there are other things to worry about.
 
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1,906
Location
Canada
Originally Posted by dave1251
If you could get the drivetrain up to operating temperature quicker it would help with your fuel economy but being cold there are other things to worry about.
Assuming wear/damage isn't an issue, would it burn less fuel to immediately put significant load on the engine, to warm it up. Or idle it until it warms up and is more efficient? It'll burn more fuel at the "significant load", but will warm up considerably faster at such point, the fuel consumption will drop rapidly. Likewise, assuming the engine will start without a block heater, will cost incrementally more (or less) to partially heat the engine up with a block heater, than it would by simply starting it and burning an additional amount of fuel to warm it? The sort of temperature increase a block heater could achieve in an hour or two at -35, for example, likely pales in comparison with just literally a few seconds of engine operation and the heat created in the block due to combustion of the fuel. I've personally mostly avoided using block heaters because if a car is in such condition that it won't start from the ambient cold without one (ie: due to weak battery, starter, etc.), I really don't want to be taking that vehicle anywhere that it can get cold and not start anyways. So its a matter of safety. 0W-xx oils, of course, mandatory in Canada.
 
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1,906
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Canada
Originally Posted by dave1251
Also the drivetrain will wear less the faster operation temp is achieved without significant load of course.
Well 'wear' can be a function of warm-up rates as well on certain kinds of parts, ie: gaskets that seal dissimilar metals. There's lots of industrial equipment for which the manufacturers specify that warm-up rates shall not exceed certain values. Steam and gas turbines come to mind. A drivetrain 'wearing out' faster may very well be justified in the context of fuel savings, or operational life limitations that are less than the probable in-service use of the equipment. ie: most cars made in the past 30 years were retired and destroyed with perfectly functional engines, but were removed from service due to accidents, technological obsolescence (ie: cash for clunkers, excess fuel consumption), or uneconomically repairable other components like interiors, transmissions, electronics, etc. Not bona fide mechanical engine wear.
 
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1,443
Location
Northeast Nebraska
Hard to say for sure without knowing what vehicle the OP is asking about but him saying slightly says it's normal. My 08 Lucerne isn't as bad as my 99 LeSabre was which I think has to do with the fact the Lucerne warms up faster, both have the 3800. The Lucerne has dropped from 15.8 to 14.5 average according to the computer since winter started but that includes warm up time in the morning and sometimes at lunch depending on how cold it is, nice getting in a warm vehicle.The interesting thing to me is how fast the OLM has dropped since winter started. I really don't want to talk about my 89 Sierra, it's to painful.
 
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4,599
Location
Manchester, England
Some curcumstances could cause this effect to go the other way based on the particular car in question. Ffor example a heavily boosted small capacity engine equipped with knock control on low octane fuel could be overfuelling heavily in hot weather to control cylinder temps, but then during very cold weather the reduced IAT and increased intercooler efficiency would allow a leaner mix and so increased MPGs. There are too many variables to apply a blanket rule here, its a case of 'suck it and see'
 
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1,162
Location
south dakota
Originally Posted by edyvw
Originally Posted by 2009Caraman
I'm kinda new to driving and was wondering what kind of penalty I can expect in extremely cold weather(-20c sustained)? Drives are typically 15mins or less. I replaced my lower intake manifold gasket and though performance has returned fuel economy has slightly dropped. It's only been a 1/2 tank though and since i did the repair it's been at least -15c every day. I'd like to hear your thoughts or observations on mileage in the cold.
What car? What oil is in the car? Is it in garage? Whatever you do, first few km's do not turn on heat and vent for 2-3km's as that delays warming up. Also, do not idle longer than necessary to put seatbelt, get accomodated. Move and move slowly, allowing transmission (assuming it is automatic) to [censored] around 2,000rpms.
Good info here. I had no idea turning on the heater would slow down engine warmup. Thank you.
 
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13,937
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...
Originally Posted by joekingcorvette
Originally Posted by edyvw
Originally Posted by 2009Caraman
I'm kinda new to driving and was wondering what kind of penalty I can expect in extremely cold weather(-20c sustained)? Drives are typically 15mins or less. I replaced my lower intake manifold gasket and though performance has returned fuel economy has slightly dropped. It's only been a 1/2 tank though and since i did the repair it's been at least -15c every day. I'd like to hear your thoughts or observations on mileage in the cold.
What car? What oil is in the car? Is it in garage? Whatever you do, first few km's do not turn on heat and vent for 2-3km's as that delays warming up. Also, do not idle longer than necessary to put seatbelt, get accomodated. Move and move slowly, allowing transmission (assuming it is automatic) to [censored] around 2,000rpms.
Good info here. I had no idea turning on the heater would slow down engine warmup. Thank you.
This must be a older car? I haven't taken precautions like that in a long long time.
 
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437
Location
Canada
Not sure if it was mentionned before but colder air = more oxygen, so the MAF will be reporting denser air and the ECU will compensate by sending more fuel in the mix so that the engine does not run lean.
 
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15,138
Location
N.H, U.S.A.
I get nearly 8 mpg less in the winter. ( 41 > 33 ) There is less energy density in the fuel ( more light fractions, volatiles) The gear lubes in the diff and final and transmission are very viscous the wheel bearing grease is very thick Engine coolant is very cold Engine will run in enrichment longer and at the slightest throttle tip in and of course, the engine oil is extremely viscous. Best you can do would be to run a block and pan heater 2-3 hours before startup and block off 70-80% of the radiator. And of course run the lightest real synthetic PAO oil allowed and the lightest gear oil allowed.
 
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