Any one hear this one before?
 

Gas up on cool mornings. Fuel is denser when cold. Gas pumps measure by volume, so if you pump when it's cold, you get more gas for your buck.

Found it here, an excerpt from Consumer Guide®:

HowStuffWorks "How to Improve Your Fuel Economy"

I heard that same thing, too. It may have been from the same source. It does seem like it would make sense. I am trying to do that, but I work all three shifts in a rotation, so I can't get a factual.

It makes sense, except gas is stored in tanks set below the frost line. Below the frost line the ground stays the same temperature the year around. So I assume that means it stays the same temperature throughout the day. Hence, no temperature change and no desnsity advantage. Years ago I had to maintain a 5000 gallon below ground gas tank on company property. The only time I ever saw any flucuation was when there was a withdrawal (maybe 3 a week). I measured that tank all hours of the day and never saw any daily variation. If there had been any variation I would have had to report it, never did, and that was up to 5000 gallons, a much large amount then you would ever get in a vehicle's tank. Now above ground tanks are a whole different thing. Another factor would be when they get the delivery which would be a different temp than was in the tank.

homeworkhome53

I understand they compensate for temperature when the fuel is delivered to the station but not when it is pumped to the car. If true, the only "strategy" I can think of here is to fill up right after a delivery on very cold days, and don't fill up right after a delivery on very hot days and maybe a couple gas molecules will drift your way :)

And hope the owner isn't ground sourcing the stations AC in the underground tank...

This is true. A local news station tested this "myth". They found a negligable difference in the temperature of the gas coming out of the nozzle between early morning, afternoon and evening.

Exactly. If you have any idea how a gas station works, it's pretty much common sense. Another factor is that it probably makes inventory control much simpler.

If anyone has ever seen a gas station in the midst of replacing it's tanks, you'd be amazed at how deep a hole has to be dug. Temperature fluctuations are minimal more than a couple of feet down.

Then again, most people lack common sense or any understanding of how they are able to go about their lives without getting stranded somewhere and starving to death.

Ground temperature thing....duh! I should have known that.

The offload from the truck could change a bit I suppose. Maybe this is why you see gas deliveries in the afternoon. LOL

Exactly! Hardly anyone understands this.

The money used to be in refining, now it all goes to getting it out of the ground in the first place (though, for example, in Saudi Arabia, it costs less than $5/bbl to pump it-- the most expensive oil I'm aware of is Alberta tar sands that run more like $70/bbl).

I have heard gas stations only make 2-3 cents per gallon. I live in WA state and our gas tax alone is 89 cents per gallon.

The OPEC nations are screwing us hard right now. Too much Arab control I think, maybe a quiet Jihad is in play to milk the Super Powers dry. There is no shortage, so whats the real deal?

Could be politian's and what they are invested in too.

I always fill up in the morning because that is the most convenient for me. Either I'm off from work or going to it, it's cooler so I don't bake when I'm pumping the gas/checking tires plus no waiting and less peripheral traffic to worry about. The temp variation thing was (I thought) geared towards above ground tanks like some in Canada. I'm not sure how it matriculated to the states but whatever. Didn't break my routine.