ok the pumps at the station tell you not to top off. Why is this? I ask this because someone at my office told me it had to do with the fuel pump or tank needing a certain amount of pressure within the tank to operate properly. Does anyone know if this is true and have I been doing any damage to my fuel system by "topping off"?

 

I have always topped off my tank as well, and i have not had any problems. But i am curious too...

 

I top mine off all the time. usually never let it below half a tank.
But I just found this link from the EPA. http://www.epa.gov/donttopoff/

 

I do it for convenience in reconciling my credit card statement.
When dining out, I roll the tip up to the next dollar.
When pumping gas, I stop on the dollar.

At over $3.00 per gal, I'm adding about a pint or quart after the auto-stop.
The truck, including the fuel pump etc... are nine years old, no issues.
Did the same with my last truck I had for 14 years, it's still on the road, saw it the other day.
And that truck would sometimes get nearly a gallon after the auto-stop.

Before that I used to watch my dad go to the next dollar.
And he was cramming another three gallons in there, back in the day.

 

i agree Raoul, i do the exact samething sometimes trying memic what Jerry Seinfeld did in his commercial and see if i can stop it at the even dollar. Here is what the EPA site FIDDY linked us to said:

You need extra room in your gas tank to allow the gasoline to expand. If you top off your tank, the extra gas may evaporate into your vehicle’s vapor collection system. That system may become fouled and will not work properly causing your vehicle to run poorly and have high gas emissions.


Sounds like the EPA is trying to scare you into doing your part to help the environment. I say go hug a tree!

 

When Seinfeld did it, it was minor league.
You got to have skilz to stop on a dollar when it's three plus per.
I do sometimes have some charges on my statement for XX.01 :o

 

I don't remember EVER not filling to even dollars.

 

I stop when it clicks off so I know (hopefully) exactly how much fuel I used since the last fill up. I know we're talking tenths of a gallon, but I'm an engineering dork and like to be as accurate as possible.

Also from the webiste fiddy linked to

- NCSU

 

True nscu just another way the oil companies are screwing us out of every penny they can!

 

I would be wary of topping off at a pump that had two lines on the nozzle.
We don't have any around here.
When we do, I'll play by the rules.

I buy gas for my small engines in 3 and 5 gallon containers that are marked on the side and the pump rings true on those.

 

I would be wary of topping off at a pump that had two lines on the nozzle.
We don't have any around here.
When we do, I'll play by the rules.
Interesting i cant say that i have every seen a pump here with two lines, that i can recall anyway.

 

Interesting i cant say that i have every seen a pump here with two lines, that i can recall anyway

 

This doesn't say anything about topping off but it is interesting. I got this in an email.
TIPS ON PUMPING GAS (Good information)
>
> I don't know what you guys are paying for gasoline.... but here
> in California we are also paying higher, up to $3.50 per gallon. 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 gallon..
>
> Here at the Kinder Morgan Pipeline where I work in San Jose , CA
> we deliver about 4 million gallons in a 24-hour period thru the
> pipeline. One day is diesel the next day is jet fuel, and gasoline,
> regular and premium grades. We have 34-storage tanks here with a total
> capacity of 16,800,000 gallons.
>
> Only buy or fill up your car or truck 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
> more dense the gasoline, when it gets warmer gasoline expands, so buying
> in the afternoon or in the evening....your gallon is not exactly a
> gallon. In the petroleum business, the specific gravity and the
> temperature of the gasoline, diesel and jet fuel, ethanol and other
> petroleum products plays an important rol! e. A 1-degree rise in
> teperature is a big deal for this business. But the service stations do
> not have temperature compensation at the pumps.
>
> 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, middle, and high. In slow mode you should be pumping on low
> speed, thereby minimizing the vapors that are created while you are
> pumping. All hoses at the pump have a vapor return. If you are pumping
> on the fast rate, some of the liquid that goes to your tank becomes
> vapor. Those vapors 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 gas tank
> is HALF FULL. The reason for this is, the more gas you have in your
> tank the less air occupying its empty space. Gasoline evaporates faster
> than you can imagine. Gasoline storage tanks have an internal floating
> roof. This roof serves as zero clearance between the gas 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 gallon is actually the exact amount
>
> Another reminder, if there is a gasoline truck pumping into the
> storage tanks when you stop to buy gas, DO NOT fill up--most likely the
> gasoline is being stirred up as the gas 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 most value for your money.
>
> DO SHARE THESE TIPS WITH OTHERS!.
>
> Fill up in the morning in the slow mode when your tank is half
> full but not when the tankers are filling the storage tanks.

 

I've been topping off for years, on almost two-dozen cars I've owned in that time, without an issue, anywhere, whatsoever.

 

Very interesting! Thanks