Got an oil change and now I get lower gas mileage...

[mycologist]

They are switching to winter gas. Everyone's mileage will suffer.

[Calvinball]

They are switching to winter gas. Everyone's mileage will suffer.

Bada bing.

[Obeisance]

Alternately, you could try to monitor your fuel usage in a different manner; I can't get reliable numbers by using the trip meter and the gas pump number, even when I let the pump turn itself off (I thought that this would give a same-fill level baseline) the computed number varies between 22-28 mpg per tank (in spite of similar driving path and habits). When I monitor, over a long time, my total gallons purchased and total miles driven and plot in excel, the slope fits with a 99% R squared to 26 mpg. I think that this method helps me to reduce calculation error from differing fuel fill amounts and other factors.

edit: also, in spite of the common knowledge about winter fuel, my plot's slope didn't appreciably change from summer to winter.. I'll have to watch the plot again this winter when I will drive a lot more to see if this holds true again.

[mycologist]

Alternately, you could try to monitor your fuel usage in a different manner; I can't get reliable numbers by using the trip meter and the gas pump number, even when I let the pump turn itself off (I thought that this would give a same-fill level baseline) the computed number varies between 22-28 mpg per tank (in spite of similar driving path and habits). When I monitor, over a long time, my total gallons purchased and total miles driven and plot in excel, the slope fits with a 99% R squared to 26 mpg. I think that this method helps me to reduce calculation error from differing fuel fill amounts and other factors.

edit: also, in spite of the common knowledge about winter fuel, my plot's slope didn't appreciably change from summer to winter.. I'll have to watch the plot again this winter when I will drive a lot more to see if this holds true again.

I like the idea of a long term average.

Here the scoop on stats though - your slope doesn't fit to a point, it fits to all the data. I.e. you R2 tells you how well it fits all the data, not what the average is of all that.

You would need to put each fill, or each week etc. as a separate observation in an anova style analysis. Use summer and winter as the factor. Then you would be comparing the summer average vs. the winter average based on sample size and distribution, and the P value would tell if there was a significant difference.

[Mikie13]

Moron, think about it for a second instead of just opening your trap immediately. Obviously you can only put the oil in one way, but I have had dealerships put too much oil in my car, put the wrong oil in my car, not put enough in my car, which would be "putting it in wrong" don't you think? I'm not an idiot, think before you respond.
Also, I haven't changed my driving habits and I still put 93 octane in the car because that's the premium in my area.

Explain yourself better next time before jumping to conclusions. Not putting enough in, is not putting enough in. If they didn't put enough in, they would have not put enough in, through the oil fill hole, correctly. If you're going to post on a public internet forum, I'm going to open my trap all I want. If you can't handle what was actually a legitimate comment that actually did make me laugh, then go to Nasioc or some other place. Nothing in my post was posted in a negative way (ergo the sarcastic little ). Get some thicker skin homeboy.

[Ruh Roh]

not sure if its true or not but ive heard that the colder weather brings less mpg. havent noticed a change in mine. i got 25 the other day

[Mikie13]

not sure if its true or not but ive heard that the colder weather brings less mpg. havent noticed a change in mine. i got 25 the other day

Can also be very true. Air is colder, ergo it is more dense. Therefore you need to compensate with more fuel (also why you feel your turbo kick in a little better in cold air...further compressing already dense air, so more of it to go boom in the cylinders).

[mycologist]

Let's stay on track please.

[nsibanez]

a few things in my opinion could affect your mpg. how much highway driving youre doing, are you behind bigger trucks to cut air resistance, too much oil, not enough, are you mixing gas
things like this have affected mine. directly after a fill up on my way to work ill get up to 30, maybe more but its because i drive carefully, and usually beind someone the whole time. then as the week progresses ill watdh it drop.
its not anything to worry about i dont think

[Ruh Roh]

Can also be very true. Air is colder, ergo it is more dense. Therefore you need to compensate with more fuel (also why you feel your turbo kick in a little better in cold air...further compressing already dense air, so more of it to go boom in the cylinders).

alright enough with all these science words!

[nsibanez]

They are switching to winter gas. Everyone's mileage will suffer.

theres winter gas? what is that? ive never heard of anything like that before. i thought gas was just gas

[nsibanez]

not sure if its true or not but ive heard that the colder weather brings less mpg. havent noticed a change in mine. i got 25 the other day

m not

its true...i think at least. all your fluids are getting colder and more viscous...
im not a science major, so i dont even know if i worded that right

[RayfieldsWRX]

My experience has always been that my turbocharged cars suddenly feel faster, as well as get lesser fuel mileage, once temps turn chilly. It's true because science.

[nsibanez]

lol minus the harder shifting

[zax]

It's likely the colder temperatures. A car's motor performance increases in the cold, but the fuel economy typically decreases.

Furthermore, the car stays in cold-start-enrichment for a longer stretch of time (before reaching operating temperature). This means more fuel is injected over the base fuel map -- the effect is similar to "Choke" for all you old guys