This from a friend in the industry..........................

Tips on Filling your Vehicles...
This is a Message received from a friend:
I don't know what you guys are paying for petrol... but here in Durban, we are also paying higher, . But my line of work is in petroleum for about 31 years now, so here are some tricks to get more of your money's worth for every litre.
Here at the Marian Hill Pipeline, where I work in Durban, we deliver about 4 million litres in a 24-hour period thru the pipeline.
One day is diesel; the next day is jet fuel, and petrol, LRP and Unleaded. We have 34-storage tanks here with a total capacity of 16,800,000 litres.
ONLY BUY OR FILL UP YOUR CAR OR BIKE IN THE EARLY MORNING WHEN THE GROUND TEMPERATURE IS STILL COLD. Remember that all service stations have their storage tanks buried below ground. The colder the ground, the denser the fuel, when it gets warmer petrol expands, so buying in the afternoon or in the evening.... your litre is not exactly a litre.
In the petroleum business, the specific gravity and the temperature of the petrol, diesel and jet fuel, ethanol and other petroleum products play an important role. A 1degree rise in temperature is a big deal for this business. But the service stations do not have temperature compensation at the pumps.
Compiled by Ramesh Patel on 16.03.2008 @ 10:00Hrs. Page 1 of 2
WHEN YOU'RE FILLING UP, DO NOT SQUEEZE THE TRIGGER OF THE NOZZLE TO A FAST MODE. If you look, you will see that the trigger has three (3) stages: low,
Compiled by Ramesh Patel on 16.03.2008 @ 10:00Hrs. Page 2 of 2
middle, and high. In slow mode, you should be pumping on low speed, thereby minimizing the vapours that are created, while you are pumping. All hoses at the pump have a vapour return. If you are pumping on the fast rate, some of the liquid that goes to your tank becomes vapour. Those vapours are being sucked up and back into the underground storage tank so you're getting less worth for your money.
ONE OF THE MOST IMPORTANT TIPS IS TO FILL UP WHEN YOUR TANK IS HALF FULL. The reason for this is, the more fuel you have in your tank, the less air occupying its empty space. Petrol evaporates faster than you can imagine. Petroleum storage tanks have an internal floating roof. This roof serves as zero clearance between the petrol and the atmosphere, so it minimizes the evaporation.
Unlike service stations, here where I work, every truck that we load is temperature compensated, so that every litre is actually the exact amount.
ANOTHER REMINDER, IF THERE IS A FUEL TRUCK PUMPING INTO THE STORAGE TANKS, WHEN YOU STOP TO BUY, DO NOT FILL UP - most likely the petrol/diesel is being stirred up as the fuel is being delivered, and you might pick up some of the dirt that normally settles on the bottom.
Hope, this will help you get the maximum value for your money.
DO SHARE THESE TIPS WITH OTHERS! LET’S SHARE INFORMATION AND BENEFIT ALL.
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Good tips and find, gives me a reason to wake up early on the weekends.

 

Good information. I have heard a lot of people say that you should fill up at half way in order to keep the fuel pump cool and working longer. Now I hear filling up sooner saves gas too
*to the gas station*

 

good advice ....

 

I have a hard time believing any of this is significant enough to bother with.

people who have been in the oil industry generally dont type IN ALL CAPS TO GET YOUR ATTENTION. In fact I don't know anyone who is 50+ years old *and thats on the low side* who talks that way.

 

Truth in this post. I am a younger guy (25) so my experience isn't quite as great as the claim in the OP but I do work at an oil company. While some of what was contained in the OP is true, I am not sure it is going to make that much of a difference, at least not measurable. I don't think we are talking about anything more than a VERY small fraction of a cent in improvement here. Especially on the density portion.

The density of gasoline (C8H18) is roughly 0.694 g / cm^3 at 300*K (K = Kelvin) and roughly 0.622 g / cm^3 at 400*K. Density shouldn't change that much relative to the ground temperature (300*K = 80*F and 400*K is 260*F). So over a temperature range of 180 degrees, you are only changing about 0.072 g / cubic cm.

What does that look like in gallons? 1 Gal = 3785.4 cm^3. The change in density gives you 272.5488 more grams at 80* than 260*. End result is over that temperature range, you gain .6 pounds. About 6 pounds are in a gallon. Sounds insignificant to me.

The only one I would really take to heart is not filling up when a tanker as at the station. Even then, it isn't that big of a deal. Cars have fuel filters and I am sure stations and pumps do too. For good reason.

 

Fuel filters do get clogged, and they don't catch everything. It's something easy to do to save a little annoyance in the long run..

.6/6 = 10%. 10% more gas is a HUGE difference.

 

It's important to note that the "half full" part of it only applies to vehicles that don't have a fill port mounted directly on top of the tank, i.e. cars. It does not apply to motorcycles, which easily exhange air for fuel.

 

agreed but on the last one i know a trucker and he said that once when he was filling up a tank he left the additive on for too long and put way too much in. thereby giving the vehicles that filled up there better gas mileage. it wasn't like an extra 10 mpg or anything but more like 3-5 mpg better than usual. don't ask me what the additive was cause i can't remember but he said that they add it at the station when they fill the tank up.

he coulda just been ****ting me too, i can't ever tell with this guy.

 

Not over 180F. IMO, that's a very small difference considering that we're talking about a temperature fluctuation in the ground of maybe 5F max. (50-55F)
That's nothing, and I'd be willing to bet that air temps outside won't change the temperature of in-ground tanks much (if at all) over the course of a day.
Above ground tanks? Certainly. In fact, when I fill my methanol tanks on a hot sunny day, I better leave some space in the tank for expansion or some dumb smoker could blow themselves to pieces.
But still probably not worth worrying about.... maybe a quart or two in 550gals.

I prefer to save money by buying one less beer per day or downgrading to a less expensive escort.