Your Gas Tank: Do You Top Up or Not?

Discussion in 'Community Discussion' started by HappyDude20, Dec 11, 2010.

  1. macrumors 68020

    HappyDude20

    Joined:
    Jul 13, 2008
    Location:
    Los Angeles, Ca
    #1
    This is something that's been subconsciously on my mind for a while now and figured bringing it to minds of others to discuss it could potentially leave me with a more informed decision when at the gas pump.

    Sometimes I fill my gas tank up completely, while other times i'll fill up the gas tank only half way. Other times, rarely, i'll only add a gallon or two at the pump.

    Sometimes the reason is money. If I find a gas station where the price is super low and my tank needs filling up, I'll add the whole 14 gallons to my Altima, which for most of 2010 gets filled up completely with about $40.

    Other times when the gas prices aren't that appealing, but need gas and perhaps don't want to make another gas trip visit i'll fill her up half way, so about 6-7 gallons for about $20. <This option seems to reoccur the most, except in the summer months when I usually fill the tank up completely due to driving a bit to the beach.

    & then there are the rarer times when I need gas but am either dead tired, or dead tired to get home so i'll stop by a gas station and simply add a gallon or two in a hurry. This situation also may occur when there's only one gas station in the area with higher prices.

    -

    The reason I felt like starting this thread was simply cause I remember hearing that filling up the gas tank completely is most beneficial for the car, and also in terms of getting the most mileage.

    If I filled up my gas tank completely on a Monday, it would most likely last me for a week and a half...for $40. While this week I added $20 on monday, needed gas earlier tonight (friday) and added $10. $30 total this week, and then some.

    Of course, all this is the intended wanted outcome of spending the least amount for gas. $30x4= $120 on gas a month...

    Iono, just figured i'm not the only one that has a personal mantra when it comes to filling up their car. :p
     
  2. macrumors 68030

    Watabou

    Joined:
    Feb 10, 2008
    Location:
    United States
    #2
    Well the more gas you have, the less mileage you actually get because of the added weight obviously. I haven't really tried that though because I get around 32 mpg which is good enough for me.

    I fill up my gas to the full because I'm too lazy to go back and fill it up again. Plus, I always fill up at Costco which is the most crowded gas station here...but, on the other hand, I get my gas at $2.9-3 per gallon which is pretty nice considering I only fill up every other week.
     
  3. macrumors 68000

    VPrime

    Joined:
    Dec 19, 2008
    Location:
    London Ontario
    #3
    When I was working I would fill up to the top..
    If I was going to the track to race, I would usually fill up half way.. Or just enough to get me there and back :D

    One thing to take note of is on most cars gas lubricates and cools the fuel pump. So leaving it empty, or very low on fuel can cause your fuel pump to fail prematurely :) So don't leave your gas tank too empty!
     
  4. thread starter macrumors 68020

    HappyDude20

    Joined:
    Jul 13, 2008
    Location:
    Los Angeles, Ca
    #4
    I remember thinking the very same thing..though never found any proof supporting this claim.

    It makes sense in a way, for some reason I also thought that the less gas, say having only 2 gallons as opposed to a full 14 gallon tank, the car will go through the gas a lot more quickly...kinda like the last water in a sink in a spiraling funnel; the funnel picks up speed and really gets rid of the water most quickly at the very end... Though this sounds like a drunken thought, aside from having no proof at all to this theory that may or may not even make sense, has come to my mind once or twice.<<<<<<< This paragraph doesn't make sense, and it's also one long sentence. I apologize.
     
  5. macrumors 601

    eawmp1

    Joined:
    Feb 19, 2008
    Location:
    FL
    #5
    Electronic fuel pumps use the gas for cooling and lubrication. In theory running on empty could cause problems. There is an old theory that if you run on empty the sediment on the bottom of the tank is concentrated and could foul the engine. As the fuel pump always sucks from the bottom and with the modern fuel filtration, this is probably bunk.

    Your car weighs less when tank is less full, so you will get better mileage as the tank empties.

    Filling the bottom 1/2 of the tank costs the same as filling the top 1/2, so unless one lives paycheck to paycheck, there is no economic benefit to not filling up.

    And NEVER top off tank after handle clicks - wasteful, bad for environment, and can block vents.
     
  6. Moderator emeritus

    Hellhammer

    Joined:
    Dec 10, 2008
    Location:
    Finland
    #6
    You have cheap gas. It's about 1.5€ per liter in Finland so 14 gallons (~53 liters) cost around 75€ (100$). I don't drive that often as I don't have my own car yet but I sometimes borrow one of my parents' cars and use that. If I have to fuel it, I never fuel it to the top because both cars have like 80L tanks so that would cost me 120€ to fill it, yuck!
     
  7. macrumors 68040

    takao

    Joined:
    Dec 25, 2003
    Location:
    Dornbirn (Austria)
    #7
    obviously having a full tank has to use more fuel simply because of the weight

    on bigger cars with 60-70 liter or more tanks it's the same as riding with a passenger



    that's also an explanation why many modern cars have a lot higher 'empty weight' than 20-30 years ago because it's simply calculated differently

    in europe for example the "empty weight" includes a 75kg driver and a 90% full fuel tank
    in the US the "curb weight" includes a full gas tank but AFAIK no driver
     
  8. macrumors 68000

    VPrime

    Joined:
    Dec 19, 2008
    Location:
    London Ontario
    #8
    It really depends on the car. My car, and quite a few others I have worked on will kill the fuel pump on empty.
     
  9. Moderator emeritus

    r.j.s

    Joined:
    Mar 7, 2007
    Location:
    Missouri
    #9
    I fill up every time. Why not, adding a little bit just means I'm going to need more soon.
     
  10. macrumors 6502a

    Joined:
    Aug 11, 2010
    #10
    I never put this much thought into it. I fill up at the cheaper cash only station on my way to work.
    If I cant get to cheap gas station, then I fill up anywhere.
    On the the gsxr, I try to only go to shell. It's that damn marketing they do.
     
  11. macrumors 6502

    Joined:
    Nov 5, 2009
    #11
    I fill it until the handle releases, usually.

    Sometimes I can't though, running a CC through the pay at the pump limits you to 75.00. A 26 gallon tank and the right fuel price sometimes means I am a gallon or two shy when I hit the limit.
     
  12. macrumors 68030

    Mr. McMac

    Joined:
    Dec 21, 2009
    Location:
    Long Island, NY
    #12
    I always use self serve and fill my tank completely.
     
  13. macrumors 68000

    dllavaneras

    Joined:
    Feb 12, 2005
    Location:
    Caracas, Venezuela
    #13
    I always top it off. The only reason for not doing so is forgetting my wallet. Gas is so ridiculously cheap (a full tank of gas costs about a dollar) that we always top off the tank.
     
  14. macrumors 601

    Phil A.

    Joined:
    Apr 2, 2006
    Location:
    Telford, UK
    #14
    That's about what it costs in the UK - current price is between £1.15 and £1.25 per litre (1.37€ to 1.49€) with prices set to rise again in the new year. It's even more expensive on the motorway (over £1.30 in some places) so if I'm caught short of fuel on a motorway I tend to just put enough in to get me by and then fill up where it's cheaper



    I had to do a double take there to realise you were talking about a dollar a tank not a gallon (which would still be incredibly cheap!). Is it subsidised by the government?
     
  15. macrumors Penryn

    rdowns

    Joined:
    Jul 11, 2003
    #15
    I fill the tank every Sunday morning. I have better things to do than drive around looking to save 3¢ a gallon or topping off my tank. I do top off the tank if a snowstorm is expected.
     
  16. macrumors 68030

    iMpathetic

    Joined:
    Oct 7, 2007
    Location:
    IMBY
    #16
    I generally top my tank off... although a 25 gallon tank that needs premium is one hell of a hit, especially at 7-8mpg around town. :eek:
     
  17. macrumors 68020

    Mac'nCheese

    Joined:
    Feb 9, 2010
    #17
    I've also heard that the more air that is in your tank, the more pressure is on the gas, sending it through the engine faster. That is why when you fill up, you notice it the needle takes a bit to move down but when you are close to empty, it moves down faster. I have no proof of this, just something I've heard before. I also live in Jersey where its against the law to pump your own gas so I have no say in the matter.
     
  18. macrumors G3

    QuarterSwede

    Joined:
    Oct 1, 2005
    Location:
    Colorado Springs, CO
    #18
    That makes no sense. Air is a lot lighter than gasoline and modern engines have some type of fuel injection which negates any pressure the gas has anyway.

    I never knew that. What an outdated law!

    As far as what I personally do, I fill 'er up to full. I've never understood why any wouldn't unless broke. It's not worth the time to save a few pennies (which you're probably wasting by driving to another station) to go to a cheaper station.
     
  19. macrumors 6502a

    Btrthnezr3

    Joined:
    Aug 5, 2010
    Location:
    Texas
    #19
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    Letting someone else fill my tank would bug me to no end. I couldn't handle some greasy embicile scratching paint or dripping fuel on my baby.

    I usually fill up all the way but I've got an 11 gallon tank and get 40+ mpgs so it's not too often.
     
  20. macrumors 68040

    steve2112

    Joined:
    Feb 20, 2009
    Location:
    East of Lyra, Northwest of Pegasus
    #20
    I just wait until I'm around 1/4 tank or so and fill up. I'm at a point where I can afford it, and I don't feel like dealing with it any more often than I have to. There is a Sam's club about 2 miles from my house that usually beats the gas stations by about 5-10 cents a gallon, so I usually stop there. Kroger has this thing where if you use their "loyalty card" and spend $100 on groceries, you get $.10/ gallon off their gas. It's usually so crowded though, that I don't use it.

    Of course, back when I was in college and had a V8 powered Oldsmobile that got about 12MPG, it was a different story. It was fun trying to scrape together enough money to feed that beast.
     
  21. macrumors 601

    Moyank24

    Joined:
    Aug 31, 2009
    Location:
    in a New York State of mind
    #21
    I went to college in New Jersey, and coming from NY I thought that was the greatest law ever! Especially in winter.

    To answer the OP's question, I always fill up the tank. A tank will last my truck most of the week and I work until 1AM so I don't want to have to put myself in a position where I'm searching for an open station in the middle of the night.

    There have been a few times when I've opted only to put a few gallons in. I work downtown and it always ticks me off that it can be up to 10 - 15 cents/gallon more than around where I live. Not a lot of $$ obviously in the scheme of things, but it annoys me. I understand about higher rent and location and stuff like that, but DAMN, that $2 I can save may go a long way sometime. :D
     
  22. Moderator emeritus

    sushi

    Joined:
    Jul 19, 2002
    Location:
    キャンプスワ&#
    #22
    Always fill up.

    Criteria: Each week or when it gets to half. Whichever comes soonest.
     
  23. macrumors 68030

    einmusiker

    Joined:
    Apr 26, 2010
    Location:
    Location: Location:
    #23
    I always fill my tank in NJ, where the prices are a good $0.30 less than NY. If I absolutely have to get gas in NY I only put $10 or so in. My Murano AWD is a bit of a gas guzzler unfortunately and I drive a LOT :(
     
  24. macrumors G5

    ucfgrad93

    Joined:
    Aug 17, 2007
    Location:
    Colorado
    #24
    I almost always completely fill my tank. The only time I don't is it is really cold outside or I'm running late for an appointment.
     
  25. macrumors 68020

    Mac'nCheese

    Joined:
    Feb 9, 2010
    #25
    Yeah, when you put it like that, you know, using facts and stuff, it does sound silly but I swear I've heard it from a few people. Maybe they are so old, it was before fuel injections. The NJ law is great in the winter but sometimes, in a rush, its silly. We still have much cheaper gas then other states, though. Probably be even less if they didn't have to staff the pumps.
     

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