Tips for WINNING at the fuel pump

[goshockers]

Hi, first post here. I was wondering if you all can share your tips for maximum fueling efficiency/accuracy at the pump?

First let me share a few I have picked up. Feel free to challenge those that seem or have been proven urban legends.

1) Fuel up at dawn/dusk/night when it's cool to minimize ozone release and fuel evaporation.

2) Don't fuel up if you see a refueling truck refilling the storage tanks as sediment and such gets churned up during this process and you can get "dirtier" tanks of gas.

3) Always use the same pump at the same gas station and fill in the exact same way for greatest accuracy on manual MPG calculations.

4) Use the lowest (slowest) notch on the handle when allowing the pump to auto-fill as running the pump wide-open allows some fuel to "vaporize" (or otherwise show as being pumped into your tank but never reaching it).

5) Never top off your tank after the pump shuts itself off as most of that extra gas will just evaporate.


These are the tips I have picked up during my research. Please share any you have or challenge some of mine. I am trying to develop the most efficient (and accurate) technique at the pump.

One thing I am wondering about: is the auto-shutoff fairly consistent? For example, if I am pumping at the same pump every time, and using the slowest notch for automatic fueling, pushing the pump in as far as it will go into my tank, am I doing everything I possibly can to make sure I am putting in the same amount of gas each time in my tank?

Thanks in advance.

[ecomodded]

I am seeing a lot of Urban gas pump Legends, of non factually threats.

For example,

the ozone release theory . just plain stupid

the dreaded fill up after the gas station finally got some fresh volatile gas in is forgetting one thing. They filter the gas before it leaves the pump.

You would want to use the slowest gas flow setting so the gas is not frothed up taking up valuable gas tank space and has absolutely nothing to do with gas evaporating on its way down the filler neck.

The extra gas that one might put in after the pump has filled and shut off would not evaporate. Gasoline cars have a sealed gas system, meaning the tank will not evaporate any fuel you put in it.

Some people fill up the gas tank until they see gas in the filler neck and make that the mark to fill too.
If you use the same gas stall every time you will always get the same reading from the filler neck as the ground may or may not be level at different gas pumps and stations.

Oh and welcome to the forum !

[reb01501]

Here is what the Honda manual has to say about filling past auto-stop:
"Stop filling the tank after the fuel nozzle automatically clicks off. Do not try to ‘‘top off’’ the tank. This leaves some room in the fuel tank for the fuel to expand with temperature changes"

Makes a little sense, I guess.
I think Tom and Ray said some tanks are equipped with fuel-vapor recovery systems that will fail if the tank if the fill tube is over filled.

I avoid using slow fill speed because I've experienced auto-stop failures when filling slowly. At best, a little puddle of gas on the ground ...

[some_other_dave]

I have experienced auto-stop failure when filling at high speed as well as low.

I have also had auto-stop only fill the tank halfway up. Even on the "second click", because I didn't believe we had used so little fuel. (I was riding with friends on a long trip in their car, which I was not familiar with.)

The auto shut-off is not consistent, even on the same pump, in my experience.

I have had problems (sputtering, loss of power, other misbehavior) when filling from a station that was being resupplied when I filled. I think it was more due to water in the fuel (which will get through filters!) than dirt. The car got much better after I had burned through that tank.

If I recall the difference in density between gasoline at 50F versus 90F, you got something like 0.1% less fuel at the higher temperatures. Low enough to be "in the noise".

-soD

[PaleMelanesian]

Roughly 1% per 10C. Gasoline has 0.000950 coefficient of thermal expansion. 0.000950*10C = 0.95% volume change

[euromodder]

Originally Posted by goshockers

1) Fuel up at dawn/dusk/night when it's cool to minimize ozone release and fuel evaporation.

Tanks are usually underground here, and as such should only have small temperature fluctuations during a day.

Delivery systems are temperature-compensated.

2) Don't fuel up if you see a refueling truck refilling the storage tanks as sediment and such gets churned up during this process and you can get "dirtier" tanks of gas.

Fuel is filtered.
What doesn't get filtered out is water though.
Pumping in fresh fuel can get water in the fuel station's tank stirred up - water which shouldn't be there in any serious quantity in the first place !

Over here, problems with excessive water in fuel tanks are few and far between, but they do happen (mostly with non-branded fuel stations) and will kill a diesel pump over time - and your mileage.

3) Always use the same pump at the same gas station and fill in the exact same way for greatest accuracy on manual MPG calculations.

This is a trick to get more consistent fill-ups, by eliminating differences between fuel stations.
The ground at the fuel station is not always completely flat.
You avoid differences in fuel delivery systems, in shut-off function, nozzle length, ...

4) Use the lowest (slowest) notch on the handle when allowing the pump to auto-fill as running the pump wide-open allows some fuel to "vaporize" (or otherwise show as being pumped into your tank but never reaching it).

I lock it fully open , and let it shut off automatically.

Pumping gas slowly also has a downside, as it means the tank is open to the atmosphere for a longer period.
There will be some evaporation during fueling either way, but with tight fitting fuel nozzles with gas fume returns, that eliminates most of the issue.


Diesel hardly foams anymore these days.
It used to foam a lot more, which could throw off the consistency when filling up.

5) Never top off your tank after the pump shuts itself off as most of that extra gas will just evaporate.

Modern cars have systems that trap and condense the evaporating gas and keep it from going into the atmosphere.

Topping off can fill that system, and leave less space for heat expansion.
Don't top off if you're not going to drive a considerable distance right after fueling - and create some space in the process.

One thing I am wondering about: is the auto-shutoff fairly consistent?

It is for me.
It's just a matter of shoving the nozzle into the tank consistently.

[PaleMelanesian]

I've found auto-shutoff to be VERY inconsistent, varying by more than a gallon regularly. That's a 10% variation in a 10 gallon tank.

The only way I've found to get a consistent fill is to manually hold the lever at the slowest possible fill rate. Only a few stations even allow such a slow fill rate - some just shut off if you try to go slowly.

[gone-ot]

...many gas stations these days WANT you to "...get-it, pay-up & go..." as QUICKLY as possible so other cars can fill-up faster (ie: more $/hour).

[ecomodded]

Gas stations use water trap filters as well as sediment filters.
Water in the gas would be more of a maintenance issue at the pump as the water trap fills up over time if its not cleaned out it would flow tank water. First time I have heard of bad gas from a fresh supply, I would think it would be the opposite with the bad gas at the bottom of the tank before the fresh gas arrives.
The water filters may of filled by the use of the bottom of the tank and by the time the fresh gas is put in the tank the filters are full.

[nemo]

The only way you can win at the fuel pump is to avoid it.