Purchasing warm fuel can cost you $$$

3rd_shift · Oct 7, 2007

Just a heads up for the rest of you.
There are some filling stations that serve warm fuel.
I should know;
I travel over 3000 miles a week from Dallas to Tulsa 5 days a week.

Here is what is wrong with it.
#1 it shrinks after you bought it, therefore you didn't get what you paid for after it shrinks significantly inside your tank.

#2 it also condenses out any water it accumulated when it cools down = water in fuel.

What to do?
Stay with your vehicle when you fill up and keep a hand on the filling nozzle to see if it warms up.
If it does, stop fueling and go to another station to finish fueling.

Just to give an example.
I can fill up my 16 foot Isuzu box truck with 30 gallon tank at a good Muskogee, Ok. filling station (Walmart Supercenter) on the north side of town where the fuel is cool going into the tank and make it back to Dallas with it.

But if I fill up at a Eufaula station that is 50 miles south of there (who's name I won't mention) I barely make it back to the north side of Dallas even though the price per gallon was the same. :huh2:

Hope this helps. :shrug:

James S · Oct 7, 2007

Gasoline does have a very high coefficient of expansion. It is possible to fill your tank, and if you top off to the top of the filler pipe and leave your car sitting in the sun for it to actually overflow! (a little bit anyway, it's not all that dramatic an expansion, just a lot more compared to other things)

I'd be more concerned though about the ethanol content of the gas from the 2 different stations. Ethanol is about 30% less powerful than gas so if one of the stations sells a blend, you'll get a lot less milage out of that than if the other station doesn't. Regardless of the heat.

3rd_shift · Oct 7, 2007

Off topic but, from what I heard, ethanol has an octane of 106, but todays engines can't do anything with that high octane rating other than oxidize and blow it out the tailpipe without getting maximum power out of it.
Only a high compression off road engine can get maximum bang for the buck from ethanol from what I heard.

I forgot to mention I was talking about diesel fuel as my 16 foot box truck is the diesel version rather than the 6.0 gas version.
My bad.

It is true that cold fuel can expand and ooze right back out after it is put in.
Up north, don't top off your tank after the pump shuts off.
Especially on a warm day with cold fuel dispensed into the tank.

jake25 · Oct 7, 2007

dont blame the gas station, they dont have heaters in their tank

they can't help it if you go and buy gas at 12pm when it might be the hottest

its not the fault of the gas station its called nature

Illum · Oct 7, 2007

I suppose in future developments tank insulation may be considered....but not to the best interest of the consumers:candle:

3rd_shift · Oct 7, 2007

Uh.... now wait a minute.
I'm only reporting what I found.
I just know what I found.
I don't know why the fuel was warm. :shrug:
It just was, and I will not purchase it again from the stations it came from.

No fuel heaters? I sure hope so.
Still, those can make things profitable for a dishonest filling station even after electrical expenses, or whatever.

This thread was meant just as a heads up for the rest of you. :grouphug:

Happy hunting on your next fuel purchase.

Marduke · Oct 7, 2007

It's just a matter of when you fill up. There is a reason that it is suggested that you fill up first thing in the morning when it's cool, and not during the day. You get more for your money if you fill up first thing, and it's better for the environment.

paulr · Oct 7, 2007

That's interesting. Sometimes when I've filled up, I've heard a burbling sound as if there were air bubbles in the fuel, and found that my apparent mileage from that fill-up was lower than from other fill-ups. I wonder if that sound could also come from the fuel being warm. I can't conveniently fill up in the early morning (if I'm driving somewhere that early, it's because I need to be somewhere and don't have time to spare) but will try to fill up in the evening after dark.

Marduke · Oct 7, 2007

Filling up late in the evening is 2nd best to morning. The tanks are still warm from the hot day, but the worst time is around 4PM or so, when the tanks and ambient air is hottest. 5AM would be the absolute best time, when tanks and air are at their coolest, right before the sun starts start heating everything up again.

James S · Oct 7, 2007

well I didn't even look up the expansion rate for diesel

Where are you people buying your gas that the tank temperature varies that much? Even here in the "deep south" I can buy gas in the afternoon and there will be condensation on the pump handle when I'm done cause the tank is underground. With it entirely under the asphalt and with the thermal mass as high as it is I dont think they can swing but a couple of degrees during the course of the day, if that. Do filling stations elsewhere have above ground tanks or something?

PhantomPhoton · Oct 7, 2007

Off the top of my head ( so if I'm wrong please correct me).
In some countries, fuel is measured by mass and not volume at the station. I believe it is in cooler northern countries where consumers would benefit from getting more bang for the buck due to the fuel being cold and therefore more dense.
Whereas I think that regulations in the US for selling fuel by mass instead of volume have been lobbied against and shot down by Oil companies because it benefits the Oil company when they sell hot fuel, which of course has less density.

MicroE · Oct 7, 2007

Here is a link to a gasoline study that you might find interesting:

http://www.ncwm.net/pdf/ooida_temp_comp_presentation.pdf

One more piece of advice beyond filling up in the morning:
If you see a truck delivering fuel to the filling station, don't stop there. The new load of fuel will stir up any debris at the bottom of the station's tank and suspend it in the fuel. Some of the debris may make it into your vehicle's fuel tank.

Illum · Oct 7, 2007

paulr said:
That's interesting. Sometimes when I've filled up, I've heard a burbling sound as if there were air bubbles in the fuel, and found that my apparent mileage from that fill-up was lower than from other fill-ups. I wonder if that sound could also come from the fuel being warm. I can't conveniently fill up in the early morning (if I'm driving somewhere that early, it's because I need to be somewhere and don't have time to spare) but will try to fill up in the evening after dark.

I've always thought the sound was gasoline swishing around the ball valve on the nozzle, :thinking:

BB · Oct 8, 2007

I have read about this issue before--and elsewhere, IIRC, (pipelines, depots, between companies, large deliveries) that the US requires the fuel volume to be temperature compensated (for tax reasons--if nothing else). The only place temperature compensation is not required is for retail sales.

The bubbling in the tank could be because there is a reserve airspace to allow room for expansion--and prevention of fuel expanding and escaping the car. You could get an extra gallon or two into some vehicles if you take a bit of time getting the last spaced filled (one van I had could take ~3.5 gallons between first shutoff and the "final fill"). I would only do that if I was on a trip and knew that I was going to use the fuel quickly before the gas could heat up and expand.

I guess too that the overflow would go into the charcoal canister (for gasoline engines) in the modern car--that solid slug of fuel can also cause filling/venting issues too...

-Bill

raythompson · Oct 8, 2007

Most of what has been posted here are myths. Nothing more.

Fuel is a large mass that takes a lot of energy to warm even one degree. This would be cost prohibitive to heat 25,000 gallons of fuel. No station is going to that expense.

The tanks are underground. The temperature will not vary more than a degree or two from the coolest part of the night to the hottest part of the day.

Trucks filling up tanks will not stir up any sediment. The fuel is highly filtered while being transported in pipes, while being delivered in the trucks, and while being delivered from the retail storage tanks. Fuel is generally very clean. Any contamination, such as water, is introduced after the fuel is delivered. Diesel fuel is even more heavily filter than gas. Ever notice the auxiliary filter and water seperator on a diesel pump?

For there to be even a quart's worth of expansion of fuel there would have to be a large temperature swing, 30 or 40 degress worth. That is just not going to happen with todays storage facilities. If you doubt that look at the average alcohol based thermometer. Compare the quantity, mass, of the bulb to the size of the indicating tube. The tube must be small and the bulb large to get a change to indicate. The total expansion in volume is less than a couple of percent. Liquid just does not expand that much over normal temperature swings.

Those tanks that vent vent because vapor pressure, not fuel volume, push fuel out the filler tubes. Vapor builds up in the tank, their is fuel in the filler neck, the fuel gets forced out.

I suspect the difference in your driving range has more to do with the conditions and your driving habits. You may also have encountered a shut off nozzle that was more sensitive and you did not have as much fuel in your tank.

greenstuffs · Oct 8, 2007

You sound like an expert :poke:

:thumbsup: thx for the clarification.

raythompson said:
Most of what has been posted here are myths. Nothing more.

Fuel is a large mass that takes a lot of energy to warm even one degree. This would be cost prohibitive to heat 25,000 gallons of fuel. No station is going to that expense.

The tanks are underground. The temperature will not vary more than a degree or two from the coolest part of the night to the hottest part of the day.

Trucks filling up tanks will not stir up any sediment. The fuel is highly filtered while being transported in pipes, while being delivered in the trucks, and while being delivered from the retail storage tanks. Fuel is generally very clean. Any contamination, such as water, is introduced after the fuel is delivered. Diesel fuel is even more heavily filter than gas. Ever notice the auxiliary filter and water seperator on a diesel pump?

For there to be even a quart's worth of expansion of fuel there would have to be a large temperature swing, 30 or 40 degress worth. That is just not going to happen with todays storage facilities. If you doubt that look at the average alcohol based thermometer. Compare the quantity, mass, of the bulb to the size of the indicating tube. The tube must be small and the bulb large to get a change to indicate. The total expansion in volume is less than a couple of percent. Liquid just does not expand that much over normal temperature swings.

Those tanks that vent vent because vapor pressure, not fuel volume, push fuel out the filler tubes. Vapor builds up in the tank, their is fuel in the filler neck, the fuel gets forced out.

I suspect the difference in your driving range has more to do with the conditions and your driving habits. You may also have encountered a shut off nozzle that was more sensitive and you did not have as much fuel in your tank.

ledlurker · Oct 9, 2007

Most fuel is delivered just like everything else in the the USA. It is done in the JUST IN TIME delivery system. The fuel is still hot from being delivered from the refinery. In some cases in can be over a 100 degrees F when delivered. The whole hoopla over the fuel expansion is that when fuel is dispensed the pumps are calibrated for 60 degrees F. So for a typical fill up you might be shorted a few cubic inches of volume which is several pennies cost to you. Auguments to make the equipment adjustable to temperature can just increase the error in most cases.

3rd_shift · Oct 9, 2007

I just know this, if it's warm going in; = it's lower mpg.
If it's cooler going in; = I get the best mpg.
This is based on over 200k of travel in the past 18+ months.
My Sprinter van is now past 140K and doing extremely well on cooler fuel as long as I "drive off the excess" right away before it expands.
I do "top off" to the top.
Just today, I filled up on some good, cold stuff in Muskogee, Ok and made it 250+ miles with it still less than at a quarter tank down here in Dallas on a 26 gallon fuel tank. :wow:
Not quite %100 accurate, but...
That is still just kickin' :rock:
Where ya fill up does seem to matter.

oo:

Happy hunting folks.

Fat, high density, and cold fuel seems to rule. :twothumbs

Purchasing warm fuel can cost you $$$

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