Does the winter mixture of gas lose efficiency?

[JHarris1385]

I can cruise at 60 to my scan gauge reading in the 13-14 range when normally that is what I get in city driving. I am used to seeing the 18-19 range on the highway. These last 3-4 tanks I have averaged a little less than 13 mpg which is down about 2 mpg. Not a lot but since I have noticed this trend from the first low mpg tank I have been driving a little too gas conscious – so really it would be worse if I was driving normal?

Is this the case with anyone else?

[MrCrowley]

Take into account that you are also consuming A LOT more gas with the cold engine startup process, and possibly winter gas mixture, lower psi tires at cold startup, harder vs. softer rubber issues, denser air/aerodynamics to push through, higher viscosity lubricants/engine/tranny/transfer case/ differentials/ bearings to decrease wheel horsepower, contraction and increased friction from any moving surfaces in contact, etc. etc. etc. Of course these could all be debatable, but they don't help- thats for sure.

All very small variables, but working together to decrease your mileage

The only benefit from the winter weather I can think of just as fast is colder, denser air. Plus, colder and denser gasoline combined and adding some efficiency to the engine after it is warmed up to allow more efficient engine output.

Yeah, winter will never allow your best mileage average. In my wife's old Acura I used to commute to work in all highway miles 2 hours round trip, I would go from a high of around 440 miles per tank in mild warm weather to around 350 per tank in the winter no matter how much babying I did while commuting.

Yeah, you could drive "normal", but when you start to get in the low 200 miles per tank, you'll see why that won't help. But the again, "normal" means a lot of different things as well.

[tom4bren]

Actually (from my limited comprehension of the topic) winter mix on fuel is actually higher in energy. The summer mix with ethanol is less efficient. MrCrowley hit the nail on the head with less efficiency of the machine in the cold environment. The only other factor that I can think of is additional rolling resistance from road conditions (wet or snowy roads).

You can play some games to attempt to recoup the loss but I doubt they will pay for themselves. Lower viscous fluids will operate more efficiently at low temperatures (better off using synthetics year round tho as they are effected less by low temps). A block heater will help on start up but won't make any difference after the engine has reached operating temperature. The one thing that would make the biggest difference is checking air pressure often. During winter when the temperatures swing dramatically, your tire pressure will be significantly effected (2-3 lbs probably). Try inflating your tires during the coldest part of the day to the lowest pressure you would like to run at (say 32 psi). Then in the afternoon the pressure should still be in the safe zone but a more optimal pressure (say 34-36 psi).

[circmand]

This post has made it occur to me what do most of you run your tires PSI wise?

[ZEUS]

Using the defroster uses the air compressor as well which could contribute to the drop in mileage.

[tom4bren]

I find that I get the most even wear when I run my tires at 34-36 psi so I try to keep them at 34 year round. That's for on road. Off road is an entirely different story.

Different tires will 'feel' or react differently so you'll have to use trial and error to find what works best for you. Just make sure you keep it in the safe zone recommended by the mfr (I'd never run over 36 just for fear of breaking a bead).