Can engine be too cold?
Thread Starter
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Tuned
Joined: Apr 2002
Posts: 260
Likes: 2
From: Apache, OK
Can engine be too cold?
I moved from central Texas to SW Oklahoma. Now my dually is getting miserable mileage, much lower than in Texas. One reason might be that it has been bitter cold and when I make a twice weekly 25 mile one way trip, the engine temperature stays at 180 and takes a long time to get there; the transmission doesn’t come off the peg (autometer gauges for everything) for nine miles and tops at 130; the engine oil lags behind engine temperature and will finally get to 180 at the end of the 25 mile trip.
Could it be that the computer is thinking the engine is never warm enough and over compensates with extra fuel? The fuel mileage loss is not trivial, 15 – 16 in Texas and 11 – 12 in Oklahoma.
Could it be that the computer is thinking the engine is never warm enough and over compensates with extra fuel? The fuel mileage loss is not trivial, 15 – 16 in Texas and 11 – 12 in Oklahoma.
More Turbo
Joined: Jun 2007
Posts: 537
Likes: 3
From: Carvel, AB, Canada
Have you got the latest engine flash? Part of what it is supposed to address is cold weather performance.
Secondly, what oil are you using. In cold temps, run 5W40 synthetic.
Third, they may be running a different winter blend of winter fuel in Oklahoma. Around where I am at, it's not unusual to loose 1 or 2 mpg just on winter fuel.
Fourth, do you always fill up at the same place? If so, try switching. Make sure though that wherever you go, they have a good turn over on their fuel.
Secondly, what oil are you using. In cold temps, run 5W40 synthetic.
Third, they may be running a different winter blend of winter fuel in Oklahoma. Around where I am at, it's not unusual to loose 1 or 2 mpg just on winter fuel.
Fourth, do you always fill up at the same place? If so, try switching. Make sure though that wherever you go, they have a good turn over on their fuel.
Thread Starter
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Tuned
Joined: Apr 2002
Posts: 260
Likes: 2
From: Apache, OK
I think I have the latest flash, although it has been about a year. It starts right up in single digit temperatures. I changed the oil at the dealership just before Christmas and used the standard Motorcraft 15W40. I’ll use the full synthetic 5W40 next time. I’ve only bought two tanks of fuel since I moved, both were from the only station in my small town that has diesel – but all the farmers buy there so it should be fairly fresh. There’s a Loves Truck Stop about 15 miles away on I44 and I’ll try a couple of tanks from there.
I don’t think the thermostat is stuck open. It comes up to 180 in a few miles and stays there in traffic, open road, and idling.
I don’t think the thermostat is stuck open. It comes up to 180 in a few miles and stays there in traffic, open road, and idling.
Logistics Pro
Joined: Mar 2007
Posts: 4,604
Likes: 4
From: Claremore, OK
Loosing 3-4 mpg tells me something has changed quite a bit...maybe driving style or the type of fuel your buying (winter compared to regular). Does TX mandate a cetane? Thus maybe your getting a lower cetane in OK than you were in TX? What is the terrain like compared to where you used to live? I don't think your thermostat is stuck open...the truck is getting up to 180F in a normal length of time. Besides where your living...what else has changed? Are you letting it idle about the same as you were when you lived in TX?
Elder User
Joined: Aug 2008
Posts: 505
Likes: 0
Try plugging in the block heater for a few hours before you run it. May not need it for start up, but it gives the engine a head start on temps. And yes, cold temps will cause your mileage to drop.
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Senior User
Joined: Apr 2004
Posts: 352
Likes: 0
From: Millbrook, AL
The problem may not be caused by the thermostat completely but it's a relatively cheap way to begin diagonosing and curing the problem you have. I don't know what year truck you have or how many miles but I used to replace the thermostat in my gas burners every 2 years when I did a coolant flush. They're just too cheap and easy to replace to leave them in the engine long enough so they can become a problem. The ability for the thermo-sensitive spring to expand and contract to control engine temp decays over time, it's not an on or off deal like a sensor. Inaccurate control of engine temp could definately be causing at least part your mileage troubles. Good luck with whatever route you take.
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Posting Guru
Joined: Nov 2008
Posts: 1,458
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From: CA Sacramento
you will loose mpg with winter fuel.
tips
block heater
latest flash
syn 5W40. walmart has syn for only $20 per G and its good oil
delete egr system or unplug your egr valve. If you unplug it you will get 2 codes with no negative effect on the eng.
tips
block heater
latest flash
syn 5W40. walmart has syn for only $20 per G and its good oil
delete egr system or unplug your egr valve. If you unplug it you will get 2 codes with no negative effect on the eng.
