well seen a thing on the news last week about the tempature of gas effecting how much gas you REALY get from the gas pump.......


the hoter the fuel in the gasstations tanks the less fuel you actualy get.... and more fuel ya get with colder fuel from the main tanks......

im curious if anyone knows HOW MUCH of a difference thier is?
definatly explains WHY i get best gas milage in the winter since the fuel tanks are colder and hoter in the summer....

they said preaty much all of us USA gas buyers are geting screwed when buying gas.......
they said canada has computer units built into the gas pumps to compensate the tempature to volume of gas.... cause they said in canada they would lose money from thier colder weather.....

sounds to me like best time to buy gas in a hoter climate is real early morning......

 

First of all, I'm pretty sure gaslone expands the warmer it gets (learned this in grade 11 physics 2 years ago so im not 100% sure). So the best time to get gas would be on a hot day, or warm morning in winter. And on our gas pumps, it says that the gas is corrected to 15 degrees celcius. The difference isn't very much. I dont think it would be more than a 50 cent difference on your weekly fill.

 

It's not the air temp that counts as far as filling up, it's the temperature of the gas in the tank under ground and how long ago and what temp the gas was in the tank truck that filled it up. Once under ground my guess is the temperature of the gas stays pretty stable.

There is more at play here than the gas temp. There is also the air intake temp and the engine temp. Maybe one of our engineering majors here can give us a definative answer.

In our northern Illinois winters, the mileage definately drops off. Once again due to several factors. One being the extended time the choke is on, another being increased friction of cold parts. Try pushing your car by hand on a warm day and again on a sub-zero day and you will see a major difference. I also tend to keep the car running with the heater on when it is colder out instead of turning it off during wait time. If I lived in Arizona (or other southern clime) I imagine it would be quite different.

 

ya main thing im wondering about is how much would it throw off my milage? by me not geting the proper ammount of gas that the pump SAYS im geting?

 

If you're seeing noticable differences in gas mileage, the temperature in the tank at the gas station is the least of your concerns. Sounds to me like someone avoiding the inevitable need to fix their car, by blaming other factors.

 

I have always gotten lower mileage in cold weather. There are lots of reasons for this:

1. Intake air will become more dense at lower temps. A 10 degree swing will not be a big difference, but 50 degrees is noticiable. Colder air = more air, which requires more fuel to maintain "optimum" combustion (O2 levels at the exhaust). Your car can adjust fuel flow, but not air flow, so it ups the fuel rate to match the air rate. There may be some air flow controls, but if there are, they don't control well on the low end. At some point, you are killing the flow of air to maintain O2 levels. My guess is there is a minimum air flow to maintain combustion. That minimum air flow will be rich in O2, so more fuel is added to keep the exhaust clean.

The opposite is true for warm air. You are not getting "enough air". That is why you add a turbo. To force more air in to match the fuel you are dumping in. That is why turbos love cool days, they can dump tons of air.

2.Your car is dumping fuel in when it is cold to get things moving (warm). Someone else mentioned waiting for the "choke" to come off.

3. In Illinois (and other states), they switch the fuel blend from summer to winter for air quality. The summer blend burns more effieciently (cleaner) than the winter blend. The summer blend also costs more to produce.

4. This may be a stretch, but cold "thick" air may impede the car travelling through it. Think of baseball. More homeruns at altitude (why pitchers don't like going to Denver) and in late summer. Less air resistance.

 

After my long a** answer, I did not even answer the original question.

Gasoline will expand and contract with temperature. The coefficient of expansion for gasoline is .00069/degree off of 60 degrees F as agreed by the oil companies. For example using a 10 gallon tank size:

at 60 F,10 gallons is10 gallons
at 90 F, a gallon is (10 gal)-(0.00069)(30 deg F) = 9.9793 gals at $3.00/gal, you lost $0.062 on the tank.
at 30 F. a gallon is (10 gal)+(.00069)(30 deg F) = 10.0207 gals at $3.00/gal, you gained $0.062 on the tank.

This formula is used for wholesale purchasing among oil companies so they pay for the "real" gallons they are buying. We consumers in the USdo not see this. In the summer, we technically are getting less fuel for our $$. In the winter we get more. Might average out for those of us who live in places where it gets cold. You guys in warm climates are paying more year round, but the difference is pretty small. If you use 10 gallons a week, you're lookin at $3.22/year. Doesn't mean much on our scale, but when you are talking millions of gallons it matters.

The link below goes to an article about this. They do mention that Canada iscompensating at the pump. Probably won't happen in the US because they are making extra $$ off the warm weather areas year round. Doubt they are going to give that up without a fight.

http://www.consumerwatchdog.org/reso...lUSAJune07.pdf

 

So this is generally the info, you may be getting jipped by the amount of gas you are getting, but it is down to the tenth or thousandth of a cent of gas. In other words, it is negligible when compared to the differences the weather makes in actual mileage. So don't worry about it essentially.

 

man it still sucks tho.LOL everyone geting screwed several ways..... the cost and then they cheating us gas......

im not blaming my bad gas milage on it but trying to see how much im usualy cheated......
they said on the news it ws typicaly a buck a tank that your cheated....

 

the number given by that earlier post says 6.2 cents per 10 gal tank.