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Summer Gas Mileage

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2K views 5 replies 4 participants last post by  mdmccallum 
#1 ·
I was hoping that someone here could explain to me the reason that my 90 gets approx'ly 25-30 miles more per tank in the summer. Is it the quality of the gas? I thought cold air was more efficient, like in the winter months. Basically I have heard a few reasons but none of them are consistent. :confused
 
#2 · (Edited)
I think it's a number of things, for one everyone around here lets their car warm up for 5 to 10 minutes every morning in the winter. They also may add stuff to the gas in the winter but I am not sure on that one. Also in the winter you have the extra load of the heater running all the time. And you engine is most effciant when it is at about 195* F (maybe a little warmer) and in the summer it gets up to temp much faster then in the winter. And there is more load on the engine when all the fluids are cold and don't want to let things turn as easily. Just some ideas.
 
#3 · (Edited)
The ECU runs your engine rich until operating temp is reached. Lower ambient temp = longer rich running time. Snow tires can cost you some mpg, so can driving through snow vs. on the asphalt.

Someone should let their car run constantly for 6 months to test the "crappy winter gas" theory. ie. no warm up time. ;)
 
#5 ·
mdmccallum said:
I was hoping that someone here could explain to me the reason that my 90 gets approx'ly 25-30 miles more per tank in the summer. Is it the quality of the gas? I thought cold air was more efficient, like in the winter months. Basically I have heard a few reasons but none of them are consistent. :confused
I don't know about Durango, but here on the Front Range they change to oxygenated gas in the winter months for less pollutants. The end result is 1-2mpg worse gas mileage in the winter months. Here's a webpage about it: http://www.nwicc.com/pages/continuing/business/ethanol/Module4.htm
 
#6 ·
Good points everyone. Thanks for the input. Chance, I don't know about the gas here but it really makes sense. Will ask around to see if we get oxygenated gas in the winter. My guess is that we do.

Mike, the heated garage is especially appealing seeing as I spend so much time there. One problem, my 90 doesn't fit in the garage.
Do any of you guys have an engine block heater/warmer for the winter? It seems that this would help keep the ECU from running rich or at least it decreased the time that it runs rich.
 
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