To top off the gas or not?
10-09-2011, 07:37 PM
#1
To top off the gas or not?
I have for more than 25 years always topped off the gas at fill ups. I was warned by a gas station attendent not to. Any reason why? I get an extra 3 gal each fill up by doing that.
10-09-2011, 07:49 PM
#4
10-09-2011, 08:46 PM
#5
Walk the walk
3 gallons seems like a lot. I would think 1.5 would even seem like a high number. It would seem the concern would be the expansion of the fuel. The air is compressible but the fuel is essentially not. The fuel is stored underground and it typically at a lower temperature than ambient and moreover typically the car. Thermal expansion of fuel in a closed environment can create very high pressures. I would suspect the thermal relief is the gas cap or the vapor collection system. More likely, if you top off your tank, the excess fuel may evaporate into the vapor collection system. That system may become fouled and will not work properly causing your vehicle to run poorly and have high exhaust emissions.
10-09-2011, 09:31 PM
#6
Instructor
Topping off not always a good idea
Topping off the tank is fine if you're going to immeditely use the fuel, for example, on a road trip. However, topping off then parking the vehicle, especially in hot weather, where the fuel expands, is begging for trouble and a really bad idea. Don't do it.
However, squeezing in an additional 3 gallons makes me question if maybe you always use the same station and same pump or perhaps maybe you're rocking the car to get all the air out of the tank. If not, then something is wrong with the backpressure sensor on the gas pump if it's consistently shutting off on you 3 gallons short of a fill-up. With our 2012 TL-Tech (and on a road trip where I'll do it) It's difficult squeeze in even 1 additional gallon without rocking the car and even then I can never get more than an additional 1½ gals in it. Usually when the pump shuts off, the tank is full. Since everything is on the credit card now, I don't even bother to try to run it out to even money.
We also never run the tank down below ¼ tank, as that invites sediment to get sucked into the fuel line. More importantly, we NEVER buy gas when the big transport truck is there to deliver fuel. Pulling fuel out of a nearly empty gas station tank is a surefire way to get water in your fuel line.
Call me eccentric if you wish, but I also do not buy fuel from any of the secondary market brands. We use only Shell & Chevron. Considering what the car cost, pinching pennies on the fuel seems awfully stupid to me.
However, squeezing in an additional 3 gallons makes me question if maybe you always use the same station and same pump or perhaps maybe you're rocking the car to get all the air out of the tank. If not, then something is wrong with the backpressure sensor on the gas pump if it's consistently shutting off on you 3 gallons short of a fill-up. With our 2012 TL-Tech (and on a road trip where I'll do it) It's difficult squeeze in even 1 additional gallon without rocking the car and even then I can never get more than an additional 1½ gals in it. Usually when the pump shuts off, the tank is full. Since everything is on the credit card now, I don't even bother to try to run it out to even money.
We also never run the tank down below ¼ tank, as that invites sediment to get sucked into the fuel line. More importantly, we NEVER buy gas when the big transport truck is there to deliver fuel. Pulling fuel out of a nearly empty gas station tank is a surefire way to get water in your fuel line.
Call me eccentric if you wish, but I also do not buy fuel from any of the secondary market brands. We use only Shell & Chevron. Considering what the car cost, pinching pennies on the fuel seems awfully stupid to me.
10-09-2011, 09:34 PM
#7
Burning Brakes
Some states it's "against the law" to top off. I personally want to wring the attendants neck when they do that, because gas winds up by dribbling down the side of my car.
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10-09-2011, 10:09 PM
#8
Do not top off. It not good for charcoal canister. Charcoal canister is designed to take fuel vapors and store them in until system purges them back into intake manifold. If raw fuel goes in there, it won't work like it is suppose to and of course you'll see CEL with EVAP code. Only solution is to replace them and they are not cheap.
10-10-2011, 05:30 AM
#11
Yes I have always seen the warnings, but thought it was just the government nanies stepping into my life (not a fan). I understand the physics of fuel expansion with temp but I thought that would apply for only hot days where there would be a big difference between the likely 40-50 degree gas and the air temp. Considering you are all thinking what I am doing is not good, I will stop doing it. I appreciate the advice.
FYI.. in every car I have ever owned I have always been able to get in an extra 2-3 gal after the gas pump clicked off, regardless of what gas station I was filling up at. I have an Ody too and I can put in an additional 4.8 gals after the click off.
If any of you don't believe me, try it at your next fill up. I never let any gas spil out as I am a nut about keeping the car clean. I will not get gas in a state that I can't do it myself (NJ), even though it is much cheaper. Call me crazy, but the gas Nazis are quick to make a mess and that will be sure to make me pissed off, not to mention I had an experience 20 years ago where a moron dented my car with the nozle because he could not aim it properly into the hole. That is messed up! Anyway I have been OCD about it after that. The old "you tocha my stuff, I breaka you face" thing from the 80's. (bad attempt at humor).
Lastly when I fill up (only at Shell or Mobile and ususally at the same stations), I too will avoid getting gas when they are getting a delivery. Also I drive about 6 miles home which burns off enough gas to create some expansion space in the tank, I guess. Maybe that is why I have never had a problem? Maybe when I fill up and then hit the road in normal driving I am buring off gas fast enough to avoid fouling anything in the gas line?
Again I appreciate all of your thoughts and assistance.
FYI.. in every car I have ever owned I have always been able to get in an extra 2-3 gal after the gas pump clicked off, regardless of what gas station I was filling up at. I have an Ody too and I can put in an additional 4.8 gals after the click off.
If any of you don't believe me, try it at your next fill up. I never let any gas spil out as I am a nut about keeping the car clean. I will not get gas in a state that I can't do it myself (NJ), even though it is much cheaper. Call me crazy, but the gas Nazis are quick to make a mess and that will be sure to make me pissed off, not to mention I had an experience 20 years ago where a moron dented my car with the nozle because he could not aim it properly into the hole. That is messed up! Anyway I have been OCD about it after that. The old "you tocha my stuff, I breaka you face" thing from the 80's. (bad attempt at humor).
Lastly when I fill up (only at Shell or Mobile and ususally at the same stations), I too will avoid getting gas when they are getting a delivery. Also I drive about 6 miles home which burns off enough gas to create some expansion space in the tank, I guess. Maybe that is why I have never had a problem? Maybe when I fill up and then hit the road in normal driving I am buring off gas fast enough to avoid fouling anything in the gas line?
Again I appreciate all of your thoughts and assistance.
10-10-2011, 06:39 AM
#12
I know on my scooter if I fill the tank to the top it will probably vapor lock on me. I could solve by drilling a hole in the top of the tank (according to the scooter forums), but I think it is just as easy to leave an inch at the top of the tank.
This link had some other info on topping off to consider... http://www.epa.gov/donttopoff/
This link had some other info on topping off to consider... http://www.epa.gov/donttopoff/
10-10-2011, 07:20 AM
#13
The Sicilian
I've always topped off my gas tanks in all my cars without issue, but they are driven immediately. As for the Mustang "NO" I do not top off the tank because it's not driven as often and is old technology.
10-10-2011, 08:41 AM
#16
I just paid $4.24 yesterday for 93 at Shell. I only top off to extend my trips between the fill ups. With further thought, it realy does not make any sense for me to do it as I never go below 1/2 tank anyway and if I need to get gas sooner, who really cares anyway? I guess I am just being dumb. After all of the comments and the link one of you provided, I won't do it anymore as there seems to be more to loose than gain. I never had any issues with any car before, including the 99TL and the 05TL which were my previous Acura models.
On a side note, after I paid for all of my mods noted in my signature, my average gas milage has stabilized at 24.9 mpg where before it was around 22 mpg, providing I am getting into it as it is lots of fun to do so!
10-10-2011, 10:14 AM
#18
Racer
I just paid $3.47 last night - hope it keeps going down!
Cost $50 to fill up - much easier to swallow than the high of $75 a couple months ago.
My car stays above the halfway mark FAR longer than when it dips below 50% - it seems as soon as it goes under the halfway mark, it drops rapidly. But as someone else said earlier, I can drive around on "F" or a good 100miles+ after I fill up w/out the needle moving.
Last edited by Steven Bell; 10-10-2011 at 09:55 PM. Reason: Merged Posts.
10-10-2011, 11:00 AM
#19
Burning Brakes
10-10-2011, 11:02 AM
#20
My car stays above the halfway mark FAR longer than when it dips below 50% - it seems as soon as it goes under the halfway mark, it drops rapidly. But as someone else said earlier, I can drive around on "F" or a good 100miles+ after I fill up w/out the needle moving.
10-10-2011, 11:04 AM
#21
Moderator
just see below and make the judgement yourself..
pro's:
you get extra milage possibly?
con's:
damage fuel pump
damage sensors
pollution
cause vapor locking.
bad for gas stations with vapor lock system.
you arent really getting the gas your paying for, vapor system kicks it and stations are charging you for gas you dont get.
waste of money.
cause more damage than good.
Source:
http://www.epa.gov/donttopoff/
Source:
http://carjake.com/learn-why-you-sho...-your-gas-tank
in short, dont top. you can round it to nearest dollar.. but dont drop more than 1 gal into your tank..
pro's:
you get extra milage possibly?
con's:
damage fuel pump
damage sensors
pollution
cause vapor locking.
bad for gas stations with vapor lock system.
you arent really getting the gas your paying for, vapor system kicks it and stations are charging you for gas you dont get.
waste of money.
cause more damage than good.
Topping off the gas tank can result in your paying for gasoline that is fed back into the station's tanks because your gas tank is full. The gas nozzle automatically clicks off when your gas tank is full. In areas of ozone nonattainment, gas station pumps are equipped with vapor recovery systems that feed back gas vapors into their tanks to prevent vapors from escaping into the air and contributing to air pollution. Any additional gas you try to pump into your tank may be drawn into the vapor line and fed back into the station’s storage tanks.
http://www.epa.gov/donttopoff/
Its a waste of money. Once you hear the first click of the gas pump, did you know any gas you pump after that isnt going into your cars tank? Youre actually paying for gas that is filling up the hose, ready to be pumped into the next customers car. Any additional gas you try to pump into your tank may be drawn into the vapor line and fed back into the stations storage tanks.
http://carjake.com/learn-why-you-sho...-your-gas-tank
in short, dont top. you can round it to nearest dollar.. but dont drop more than 1 gal into your tank..
The following 2 users liked this post by potmilkz:
Acura_Dude (10-10-2011),
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10-10-2011, 11:23 AM
#22
There are only two state in the US that do not allow you to pump your own gas. Oregon and New Jersey. I live in Oregon, so even if I wanted to I can't fill the tank all the way. But now that I know it's going to cost me more $$ (thanks potmilkz), if I catch anyone doing this on my car I will kick them in the shin.
10-10-2011, 12:39 PM
#24
an adult perspective
I have topped off the tank of every vehicle I've owned since moving back to the states in 1990. For the TL, as was the case in the CL, I usually get around 3 additional gallons after the auto-fuel shut off (and always hand on handle contact). The only car this ever caused a problem with was my 2000 Maxima. After 221+k miles in the CL, and after recently crossing the 65K miles mark in the TL, there has never been one issue of any kind ... let alone one associated with topping off. The only way I seem to get different results is because of the tension in the handles themselves at the stations ... some are easier to use to achieve a slow flow than others are.
And for those citing self-proclaimed experts ... I always remove the nozzle from the normal full insertion position to ensure the flow of gas is going into the tank, and not staying in the hose or going into the stations' storage tanks. I did not select that option when I purchased the car.
My needle usually remains on the "F" mark until I've reached roughly 131 miles before it drops below the white hash.
And for those citing self-proclaimed experts ... I always remove the nozzle from the normal full insertion position to ensure the flow of gas is going into the tank, and not staying in the hose or going into the stations' storage tanks. I did not select that option when I purchased the car.
My needle usually remains on the "F" mark until I've reached roughly 131 miles before it drops below the white hash.
Last edited by Six Shifter; 10-10-2011 at 12:46 PM.
10-10-2011, 01:08 PM
#25
Racer
10-10-2011, 03:07 PM
#26
Moderator
I have topped off the tank of every vehicle I've owned since moving back to the states in 1990. For the TL, as was the case in the CL, I usually get around 3 additional gallons after the auto-fuel shut off (and always hand on handle contact). The only car this ever caused a problem with was my 2000 Maxima. After 221+k miles in the CL, and after recently crossing the 65K miles mark in the TL, there has never been one issue of any kind ... let alone one associated with topping off. The only way I seem to get different results is because of the tension in the handles themselves at the stations ... some are easier to use to achieve a slow flow than others are.
And for those citing self-proclaimed experts ... I always remove the nozzle from the normal full insertion position to ensure the flow of gas is going into the tank, and not staying in the hose or going into the stations' storage tanks. I did not select that option when I purchased the car.
My needle usually remains on the "F" mark until I've reached roughly 131 miles before it drops below the white hash.
And for those citing self-proclaimed experts ... I always remove the nozzle from the normal full insertion position to ensure the flow of gas is going into the tank, and not staying in the hose or going into the stations' storage tanks. I did not select that option when I purchased the car.
My needle usually remains on the "F" mark until I've reached roughly 131 miles before it drops below the white hash.
and no, its not self proclaiming experts.. its facts with proven results. Facts that are coming from EPA directly.
just because you have been doing it for so many years does not mean you were doing it correctly..
there is a big difference between opinion and actual fact..
10-10-2011, 03:49 PM
#27
Senior Moderator
Ive been topping off my tanks for over a million miles of driving now and never an issue. Been doing it on my 2gtl for 450k miles and never a issue.
10-10-2011, 03:52 PM
#28
Moderator
but the question is.. do you top off an extra 3 gallons on to you already filled 16 gal tank.. remember, our cars from when the gas light turns on is about 14-15 gal. with an extra 2 gal reserve tank. that brings it up to aboug 17 gal.
if you put that together plus an additional 3 gal your running close to 20 gal tank... on a car that is only rated max 18 gal.
but yea, topping off alittle is fine, topping of 2-3 gal is a problem.
10-10-2011, 04:18 PM
#29
3.09 here in GA 
... but on topic, topping off has never given me any problems.. but majority rule I suppose. We dont have warning signs around here so this is new info to me.
... but on topic, topping off has never given me any problems.. but majority rule I suppose. We dont have warning signs around here so this is new info to me.
10-10-2011, 04:44 PM
#30
an adult perspective
I have questioned the actual size of the tank since my 2nd fill-up returned over 500 miles of highway driving. I have put 17 gallons of gas into the car without the low-fuel warning light ever lighting up on a regular basis, which is totally inconsistent with what the manual says should be the case.
and just because it is 'written' by some source doesn't make it a fact ... unless you actually believe in Wikipedia ... or Obama care. My vette even takes an additional 1+ gallon after the turn-off ... and I've never deposited one drop on the fender from overfilling.
and just because it is 'written' by some source doesn't make it a fact ... unless you actually believe in Wikipedia ... or Obama care. My vette even takes an additional 1+ gallon after the turn-off ... and I've never deposited one drop on the fender from overfilling.
10-10-2011, 07:43 PM
#31
Moderator
I have put 17 gallons of gas into the car without the low-fuel warning light ever lighting up on a regular basis, which is totally inconsistent with what the manual says should be the case.
2009-2011 for SHAWD rated 17 / 25 mpg
the source is from EPA directly. you believe what you want. They make no profit into telling you not to spend more money.. lol
why take a risk to damage your car when you can just simply not top off? is it really that hard to resist topping off?
again, all the facts are here, you risk damaging gas pumps, your car and the environment... for what? extra gallon or two of gas?
there is absoluetly no problem with topping off a little, but when your talking about 2-3 gal top off? then thats too much..
10-11-2011, 10:46 AM
#32
$3.09 a gallon??? This is why we need to pump our own gas here in Oregon. I just paid $4.09 (93octaine, 76, close to freeway). The least you could pay right now in Portland is $3.42 for regular about 25 miles away from my house.
10-11-2011, 01:52 PM
#33
Burning Brakes
Here in the soprano state 3.04 ish for regular. It's not that you pump it or not pump it, it's how much as your gas taxes per gallon.
10-11-2011, 09:15 PM
#35
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^^^ Good point.
It starts with regular fuel. Here in Kansas City, premium gas is 22 cents higher than regular. But while I was visiting my finacee, gas was $2.99 for regular in Columbia, MO (home of the University of Missouri). I paid $3.20 for premium there.
It starts with regular fuel. Here in Kansas City, premium gas is 22 cents higher than regular. But while I was visiting my finacee, gas was $2.99 for regular in Columbia, MO (home of the University of Missouri). I paid $3.20 for premium there.
10-14-2011, 08:42 PM
#36
Instructor
I honestly do not see how on God's green Earth the guy was able to consistently squeeze in another THREE WHOLE GALLONS (!!) after the automatic pump shut off unless 2+ gallons of it is going on the ground or his filler neck is pinched, causing excessive back pressure. Something is wrong with what he's telling us. Coming back from Austin today I stopped in Columbus (TX) for fuel (Shell). I wasn't empty, but getting close to ¼ tank. The pump auto-shut-off at 13.234 gals. - with considerable conscious effort, squeezing of the pump trigger (perhaps 10 times) and rocking the car as hard as I could ('12 TL) the most I could squeeze in was another ½ gallon. I ordinarily would never do this, for all of the reasons stated above, but since I was on the road I knew there was no danger of expansion & potential damage. Based on my own results, IMO the OP is FOS. I'm not here to argue with him, merely to say that his claimed experience does not (at all) parallel anyone elses.
Last edited by Cap'n Preshoot; 10-14-2011 at 08:52 PM.
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