Decreased MPG

[attrapereves]

My black sonic has around 1700 miles on it. I was getting about 26MPG 30%HWY/70%CITY. I changed the oil around 1500mi. Ever since, I have been getting only around 23-24MPG. Could new oil be causing a lower MPG than before? I'm using Mobil 1 full-syn, so it's a good oil. Could the change to cold weather have something to do with it as well?

 

[River_Rat]

Assuming that you filled it with the proper weight and amount of oil, the colder weather probably has more to do with it than anything. Now that I look at your post again, you really don't even have enough miles in to get a decent average.

 

[sx sonic]

Check the thread in my Sig for more info.

As RiverRat said colder temps=worse mpg. It's a two fold dilemma, even with identical drives colder weather lowers mpgs. Also colder weather usually means habits that bring worse fuel economy, idling to warm up the car, inclement weather, sitting bc of accidents, etc.

Also knowing how you track your economy helps.

My economy has decreased slightly this month, this tank alone looks to have dropped a few mpg since the last tank (i fill up weekly btw). My drive has not changed much but trips have.

BTW one stint of stop and go traffic or one long WOT or warming up the car 1 mourning can account for
that variance if you didn't do the same thing the tank before.

It's probably nothing to worry about just the nature of the beast. Make sure your oil level and tire pressure are ok and keep logging your mileage. And no a proper oil change will not result in worse mpg, quality synthetics are actually marginally effective at yielding better fuel economy (barely noticeable, if that).

 

[ahtoxa]

Cold weather usually means the oil is thicker at startup thus requiring slightly more energy to circulate. There are longer idling times in some cases. Also, depending on where you live, most northern climates go to a winter blend gasoline, which contains more ethanol. That gives you worse gas mileage.

Lots of variables.

 

[KartRacer]

Thinking about lower MPG in colder temps. On another thread there was a implication that the computer enriches fuel mixture to keep heat in our small engines.
Is this the thought process? I too have seen a drop in the last week as we experience very cold temps however no idling, warming up, "car is kept in warm garage". If the computers enriches the fuel mixture to keep heat in the engine, would partially blocking airflow improve the problem? Then again why would the car maker not put a system in place to do just that?

 

[attrapereves]

My car doesn't do so well in the city. I'd say its been getting about 22mpg. However, driving 65 on the highway, I got around 33. Speeding up to 75, it lowered to 28. Goes to show you that speeds above 65 really do diminish fuel economy.

 

[ahtoxa]

If you want to get granular about it, any speed above 40-45 diminishes fuel. Those are the most optimal speeds if you want to see the bet mpg.