Just an FYI - You should never "top off" the fuel tank.

[Fyrefly]

I believe the environmental and "spending money for product you don't buy" risks aren't as high as the risks of overfilling the tank.

As people have mentioned, gasoline needs a little air to compress, and the vaporizer is just that - it deals with vapors. If you overflow your tank and liquid gasoline spills in, you're in trouble.

When my dad taught me to drive, even before all the high gas nonsense we've had in the past several years, he told me never top it off. Not to avoid paying extra to "the man", but to avoid damage.

I wanted to provide sources for that reason, not because I believe the gas companies are in some grand conspiracy theory to rob you of gas, though it is logical that they probably have some overflow shutoff procedures in place.

 

[cm8]

My dh used to do this to the point he would shake the car to get "every drop" in the tank. The kids and I made such a stink about it he finally stopped.

I know someone that used to do that as well, except they called it rocking the tank they also said that it got them more gas than what they paid for


Not to insinuate that is what your husband did but just what I was told by someone who did it

 

[drinkme]

I remember years ago my dh driving further to get gas that was 2 cents cheaper, then topping it off and spilling gas all over the ground. UGH!

 

[seashoreCM]

Some gas nozzle shutoff sensors have a thin tube with constant suction. When liquid get sucked in then the nozzle shuts off. Some nozzles also have a suction system to reduce vapors released to the atmosphere. There have been isolated instances when the gas station operator set the suction so high that gas was sucked into these extra tubes and returned to the storage tanks, shortweighting the gasoline delivery to the customer.

The shutoff sensor has a small enough tube that a negligible amount of gas will be sucked back if it is working correctly. If you lift the nozzle from the tank filler pipe as soon as it shuts off, you further reduce this suck back. Then after the foaming subsides in the filler you can re-insert the nozzle and round it to the next dollar if you wish.

Disney hints: http://www.cockam.com/disney.htm

 

[HeatherAnn23]

Yup - here in Oregon not only can we not pump our own gas, but it is against the law for them to top off our tanks. The topping off became law a year or so ago.

And we can and do get out of the car. Even though we do not need to pump, many stations still make you pay inside. I'm in the middle of the state, maybe they are touchyer about it near the borders where people don't know the routine.

 

[Purseval]

Yup - here in Oregon not only can we not pump our own gas, but it is against the law for them to top off our tanks.

Ignoring the nanny-state mentality that would make a law like that, think back to the original premise of a self-service gasoline station. It was supposedly done to reduce labor costs and keep the price of gasoline down. Yet, by and large, gas prices in states that have full service stations are no different than states where you are forced to pump your own gas. Sounds like some group did a good job of lobbying

 

[Purseval]

Some gas nozzle shutoff sensors have a thin tube with constant suction. When liquid get sucked in then the nozzle shuts off. Some nozzles also have a suction system to reduce vapors released to the atmosphere. There have been isolated instances when the gas station operator set the suction so high that gas was sucked into these extra tubes, shortweighting the gasoline delivery to the customer.

But when the OP wrote about free gas for the station she wasn't intimating criminal behavior she just saw it as a consequence of trying to top off your tank, which isn't truly the case.

 

[bartleby1]

Ignoring the nanny-state mentality that would make a law like that, think back to the original premise of a self-service gasoline station. It was supposedly done to reduce labor costs and keep the price of gasoline down. Yet, by and large, gas prices in states that have full service stations are no different than states where you are forced to pump your own gas. Sounds like some group did a good job of lobbying

I don't know how true it is, but someone I know who owned a gas station in NJ told me that if NJ went to self-serve, the gas rates would increase due to insurance costs to cover people pumping their own. I have NO idea if this is true or not, but I do know that NJ's gas prices are generally on the lower side when compared to most states, we don't have to pump it ourselves, AND it keeps many people employed. Win-win situation all the way around!

 

[Purseval]

I don't know how true it is, but someone I know who owned a gas station in NJ told me that if NJ went to self-serve, the gas rates would increase due to insurance costs to cover people pumping their own. I have NO idea if this is true or not, but I do know that NJ's gas prices are generally on the lower side when compared to most states, we don't have to pump it ourselves, AND it keeps many people employed. Win-win situation all the way around!

NJ is the state I had in mind when I posted. I was raised there and still have many family members living there.

 

[seashoreCM]

But when the OP wrote about free gas for the station she wasn't intimating criminal behavior she just saw it as a consequence of trying to top off your tank, which isn't truly the case.

When topping off your tank the nozzle goes through more automatic shutoff sequences and if it relies on liquid suction then more instances per pumping session when each time perhaps half a cc (cubic centimeter; mililiter; 1000 ml = 1 liter) if that is taken back.