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Tue Feb 13, 2018, 02:43 PM

Keep the gas tank always at least half full of gas

One book says. (Another book, "Girls auto clinic," says fill up when it's one quarter full)

"Why? A mostly empty tank allows water vapor to accumulate inside the tank and along the fuel line. Also, most tanks have a layer of sediment sitting at their bottom; when you're draining the dregs, so to speak, of your gas tank, the gas from the bottom of the tank brings the sediment with it. When you have water or sediment in the fuel system the engine starts to idle roughly or even stall. "

(From "Every woman's quick and easy car care," by Bridget Kachur, 2002.)

What say you, my fellow DUers?

41 replies, 2644 views

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Arrow 41 replies Author Time Post
Reply Keep the gas tank always at least half full of gas (Original post)
raccoon Feb 2018 OP
hlthe2b Feb 2018 #1
Hortensis Feb 2018 #24
marybourg Feb 2018 #2
JustABozoOnThisBus Feb 2018 #8
raccoon Feb 2018 #11
Egnever Feb 2018 #3
OxQQme Feb 2018 #18
phylny Feb 2018 #23
ProudLib72 Feb 2018 #33
ileus Feb 2018 #4
lagomorph777 Feb 2018 #5
ProfessorGAC Feb 2018 #6
genxlib Feb 2018 #7
LisaM Feb 2018 #28
Yonnie3 Feb 2018 #9
dewsgirl Feb 2018 #10
Codeine Feb 2018 #13
Cirque du So-What Feb 2018 #16
zipplewrath Feb 2018 #14
dewsgirl Feb 2018 #20
zipplewrath Feb 2018 #22
niyad Feb 2018 #12
planetc Feb 2018 #15
Cairycat Feb 2018 #17
misanthrope Feb 2018 #30
sarcasmo Feb 2018 #19
Kaleva Feb 2018 #21
Control-Z Feb 2018 #25
Hekate Feb 2018 #26
jberryhill Feb 2018 #27
dem4decades Feb 2018 #29
unblock Feb 2018 #31
TheBlackAdder Feb 2018 #32
ProudLib72 Feb 2018 #34
Wounded Bear Feb 2018 #38
ProudLib72 Feb 2018 #39
tavernier Feb 2018 #35
Auggie Feb 2018 #36
Wounded Bear Feb 2018 #37
Blue Owl Feb 2018 #40
Generic Brad Feb 2018 #41

Response to raccoon (Original post)

Tue Feb 13, 2018, 02:46 PM

1. Well, I always try to keep it full in wintertime- neverknow when you couldbe stranded on a closed

road or interstate out here in heavy snow, if you travel a lot or commute along the front range. Full tank means heat (as long as you keep the tailpipe clear).

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Response to hlthe2b (Reply #1)

Tue Feb 13, 2018, 06:14 PM

24. Yes. Also when Trump is insulting NK or if perhaps Russia

is unable to achieve its goals through him and possibly deciding on other ways.

Most people's work doesn't take them into badly policed areas as mine used to do, but minimizing chances of breaking down in those areas is another basic survival tactic.

I did once. The man who approached just a day or two after riots in East LA on a dead, deserted business street to help me did help me. I shrugged and rolled down my window for him in response to his trying to talk to me because it was a coin toss. I knew if he meant harm not rolling it down would only delay him a short while, and, hey, I didn't want to insult him if he (probably!) meant well.

He's not my only experience over some years, and the others did also. Human nature was weighted on my side, not luck, but better to keep that tank topped up and car tuned.

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Response to raccoon (Original post)

Tue Feb 13, 2018, 02:52 PM

2. "dregs". nt

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Response to marybourg (Reply #2)

Tue Feb 13, 2018, 03:06 PM

8. You can smuggle dregs in your gas tank, but there's not much profit in it.

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Response to marybourg (Reply #2)

Tue Feb 13, 2018, 03:16 PM

11. Thanks. I didn't catch that nt

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Response to raccoon (Original post)

Tue Feb 13, 2018, 02:55 PM

3. There is a filter between the gass tank and the engine to block sediment.

 

not sure how keeping the tank full or not will have any impact whatsoever. Maybe the filter would last longer but if the sediment is not getting filtered it is just building up in the tank. The idea there would be less just because you kept the tank full seems silly to me.

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Response to Egnever (Reply #3)

Tue Feb 13, 2018, 04:37 PM

18. Google 'fuel filter replacement' for your car

and get back to us.

This is for my Ford Focus --> https://www.google.com/search?ei=EUiDWvPkL4eA0wKpjLi4CQ&q=fuel+filter+replacement+cost+ford+focus&oq=fuel+filter+replacement+cost+ford&gs_l=psy-ab.1.3.0i22i30k1l4.6288.13013.0.17700.5.5.0.0.0.0.106.453.4j1.5.0....0...1.1.64.psy-ab..0.5.450...0.0.bPE9nHSyovM


Water in the gas=bad!
Many cars have the filter exposed to the elements.
Water freezes up in the system thereby blocking flow.
The condensation spoken of as a result of a low gas level is real.

Debris in gas tank=bad!
Most fuel pumps are located inside the gas tank with a somewhat coarser pre-filter of their own.
If that gets plugged up.....whoa!

Replacement cost for my car --> https://www.google.com/search?
>"The average cost for a Ford Focus Fuel Pump Replacement is between $552 and $924. Labor costs are estimated between $180 and $256 while parts are priced between $372 and $668. Estimate does not include taxes and fees."<

ei=ikiDWvqgJani0gK6maXQDg&q=fuel+pump+replacement+cost+ford+focus&oq=fuel++replacement+cost+ford+focus&gs_l=psy-ab.1.0.0i7i30k1l2j0i8i30k1l8.462446.464162.0.469185.6.6.0.0.0.0.115.466.5j1.6.0....0...1.1.64.psy-ab..0.6.463...0i8i7i30k1.0.HTjWxqKAEGE


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Response to OxQQme (Reply #18)

Tue Feb 13, 2018, 06:09 PM

23. My husband works for an oil company.

He also advises me NOT to stop at a gas station when it is getting a delivery, due to sediment that might get stirred up. Yes, there are filters at the gas station and in your car. Yes, they don't always work well.

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Response to OxQQme (Reply #18)

Tue Feb 13, 2018, 07:56 PM

33. I replaced my fuel filter for $25 bucks at a campsite

Got some fuel on me and fuel on the ground (worried about that since it was summer). Other than that, it was cheap and easy.

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Response to raccoon (Original post)

Tue Feb 13, 2018, 02:55 PM

4. We have 4 vehicles and have for a while now (10+ years)

Two sit most all the time, they may have full tanks, they may have a nearly empty tank for weeks or even months. They always just start up and run even with the crappy old corn blend they force on us.

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Response to raccoon (Original post)

Tue Feb 13, 2018, 02:57 PM

5. You never know when you might need to suddenly flee the country.

I doubt our neighbors are ready for a massive refugee influx. This is scary shit.

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Response to raccoon (Original post)

Tue Feb 13, 2018, 02:59 PM

6. This Seems Like An Old Concern

While being down to vapors in the winter is probably unwise, the ethanol content in today's gas prevents at least some of the water from separating. The water/ethanol partition is actually reasonably soluble in gasoline.

Then, almost ALL (and by law in most states) have water content monitors on the tanks at the gas stations. The most common source of water in a car gas tank in the past was from free, separated water in the bulk tanks undergound. Today, there is a sump and draw system so that if rain water were to get in while loading those tanks from the truck, there is way to draw bulk water, detected by conductivity, from the bottom of the tank. The driver of the truck has that knowledge and capability.

So, this was probably something that was a bigger deal 40 years ago then it is today.

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Response to raccoon (Original post)

Tue Feb 13, 2018, 03:03 PM

7. I think this may be outdated

I remember when cars were a great deal less reliable than they are now. Some of my family cars in 80's were a crap shoot to start on any given day. Once started, they were a crap shoot to shut off without run-on knocking.

Now, both of my hybrids shut-off and on my themselves without blinking an eye.

I get the sense that gas is much cleaner and better filtered as well.

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Response to genxlib (Reply #7)

Tue Feb 13, 2018, 06:38 PM

28. Yeah, I think it's outdated, because I definitely remember hearing this.

I've been in a car that ran out of gas (not mine!) and while it ended up being a rather humorous experience with two older women barging into a working class bar in Indiana in the middle of the day and demanding someone siphon gas from a lawnmower into the car we were driving, it's not an experience I'd care to repeat, so I pretend it's still relevant and fill up at the 1/2 empty mark!

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Response to raccoon (Original post)

Tue Feb 13, 2018, 03:07 PM

9. nope

Modern fuels and fuel systems don't do this.

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Response to raccoon (Original post)

Tue Feb 13, 2018, 03:14 PM

10. Running your car to often with a low amount of gas,

Will ruin your fuel pump.

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Response to dewsgirl (Reply #10)

Tue Feb 13, 2018, 03:29 PM

13. How?

I can see running out might damage a pump but what does running low do?

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Response to Codeine (Reply #13)

Tue Feb 13, 2018, 04:30 PM

16. The fuel pump is cooled by the liquid fuel

Running low can cause the fuel pump to run hotter, shortening its life (and the lives of everyone in the car if it causes a fire, although I've never heard of that happening).

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Response to dewsgirl (Reply #10)

Tue Feb 13, 2018, 03:30 PM

14. Only if you actually empty the tank

Being low isn't the problem, actually running "dry" is. It's actually a bigger problem these days than just the fuel pump too. Since most cars are fuel injected, if you actually run out of gas, it can be a pain to get the system purged and running again.

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Response to zipplewrath (Reply #14)

Tue Feb 13, 2018, 05:59 PM

20. My husband is a part time mechanic, he constantly

Used to tell me that. He tells our 20 yr old son that all the time now.
Thank you, maybe he just doesn't want us running out of gas. Our oldest son and I both love politics, can't stand anything to do with mechanics. My husband and 14 yr old loathe politics, love everything and anything car related.

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Response to dewsgirl (Reply #20)

Tue Feb 13, 2018, 06:06 PM

22. Old advice

To some extent, this is old advice. There are better, more complete, filtration systems today. Also, fuel additives to some extent do a better job of dealing with water in fuel. The pumps do a bit better at filtering it out as well. That said, I suspect a case could be made that the impact of actually running the system dry are more severe today than in the carburetor days. And yeah, a good way to avoid running out of gas is to fill it up well before it gets empty. But 2 gallons will take me 50 miles, so I'm a bit comfortable going a tad lower than that.

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Response to raccoon (Original post)

Tue Feb 13, 2018, 03:27 PM

12. I always tried to fill my tank when it got to half--mainly because it was a small tank,

and I did a lot of driving in the southwest--with lots of areas with few gas stations.

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Response to raccoon (Original post)

Tue Feb 13, 2018, 03:47 PM

15. In 1986, a guy told me to keep it at least half full. This was my first new car.

So I always filled it when it was half down. The car lasted 25 years. When it was 23 or so, its fuel valve failed, and the car stopped. So I have no idea whether there's any correlation between fullish gas tanks and longevity, but I feel it couldn't hurt to keep the tank topped up.

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Response to raccoon (Original post)

Tue Feb 13, 2018, 04:35 PM

17. My cars have always seemed to get better MPG when more than half full

that's a good enough reason for me. Plus now I have a small car and my favorite gas station gives a 10 cent discount for cash, so I don't have to have a lot of cash to fill up.

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Response to Cairycat (Reply #17)

Tue Feb 13, 2018, 06:58 PM

30. That's interesting considering

the added weight from the half tank of gasoline, which weighs in at just over 6 pounds a gallon. For reference, water is 8-plus pounds per gallon.

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Response to raccoon (Original post)

Tue Feb 13, 2018, 04:39 PM

19. Winter rule, always half a tank.

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Response to raccoon (Original post)

Tue Feb 13, 2018, 06:04 PM

21. Some misinformation posted in this thread

While fuel pumps are cooled and lubricated by passing fuel, it will be cooled the same regardless of how much gas is in the tank. A full tank doesn't provide extra cooling and lubrication in comparison to an almost empty one. One would have to run out of gas several times before damage to the fuel pump may occur.

Dirt and debris may accumulate at the bottom of the tank, As almost all cars have the fuel pump located in the tank and the fuel pump picks up the gas very near lowest part of the tank, it will suck up dirt and debris regardless of how full or empty the tank is. Fuel pumps have an intake screen and there is usually a fuel filter near the engine.

A small of amount of moisture in the tank is normal and it really doesn't make much of a difference if the tank is kept mostly full or not. The volume of a 20 gallon tank isn't much (2.67 cu. ft.) and even if the tank were empty and the humidity 100%, the amount of moisture in that tank would be negligible. And for condensation to happen in the first place, the tank would have to be colder then the air being drawn in. If there is very little difference in temperature between the tank and air, then very little condensation will occur regardless of how full or empty the tank is. Also, cold air holds far less moisture then what an equal amount of warm air is capable of holding. A person in Florida driving around in summer with a tank less then 1/2 full much of the time MIGHT end up with more condensation in the tank then a person in Wisconsin driving in winter with a less then 1/2 full tank much of the time. Products like Sea Foam and ISO-Heet should be added to the tank as directed and be part of a regular vehicle maintenance program. If one has more then a normal amount of water in the tank, a leaky fuel cap may be the culprit.

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Response to raccoon (Original post)

Tue Feb 13, 2018, 06:30 PM

25. I was frequently reminded (by my foster father)

that it cost the same to fill the top half of the tank as the bottom half. But this was about being a broke teenager who drove on fumes and ran out of gas far too often.

It was good advice and has served me well over the years. Lol.

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Response to raccoon (Original post)

Tue Feb 13, 2018, 06:34 PM

26. Quick evacuation or getaway in case of emergency

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Response to raccoon (Original post)

Tue Feb 13, 2018, 06:37 PM

27. That is really bad advice


Instead, you should make sure the tank isn't more than half empty.

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Response to raccoon (Original post)

Tue Feb 13, 2018, 06:43 PM

29. There was an accident last year on the interstate near me, the traffic was shut down for hours.

After the accident was cleared it took hours to clear up the cars that had run out of gas waiting.

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Response to raccoon (Original post)

Tue Feb 13, 2018, 07:14 PM

31. just to be devil's advocate, keeping your tank on the full side lowers fuel efficiency

if your carrying around an extra 8 gallons of gas, that's close to 50 extra pounds of weight (a gallon of gas is about 6.3 pounds), which reduces your miles per gallon by about 1%.

for most cars we're probably not talking about an extra 8 gallons.
filling up when your tank is half empty means on average you're driving with a tank 3/4 full.
fliling up when you get down to fumes means on average you're driving with a tank 1/2 fill.
the difference is 1/4 tank, which is only 8 gallons if your tank holds 32 gallons, which is a rather large tank.
f150 or hummer size. most tanks are smaller.

so the savings would be a bit less, but just to ball park it, figure you're increasing your gas costs by almost 1% by carrying around that extra gas.

you could save even more by not filling it up all the way, at the obvious expense of having to make more stops at a gas station.


for me it's not worth it, for convenience i fill it up all the way. when i get to about 1/4 tank i'll find a cheap gas station if it's convenient just to avoid the risk of *needing* to stop for gas when it's not convenient or cheap.

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Response to raccoon (Original post)

Tue Feb 13, 2018, 07:51 PM

32. Regardless of your precautions, you are more likely to get a bad batch of gas from the station.

.


Sure, during the wintertime you could get a gas line freeze, which can be resolved by placing an air heat source under the car for a little while. Been there, done that. Older gas stations, often have issues with their tanks that might allow seepage.

But, you are at more risk getting gas from the gas station. While Brand-X stations seem fugazi, name brand stations can also get bad gas as well. Most stations that are privately owned have contracts to deliver a certain amount of gas a month. If they need more, they are allowed to get their gasoline from any supplier. So, while you buy Exxon gas, you might actually get LukOil gas. Also, sine there are a limited amount of refineries, if there is a long distance to deliver the gas, one supplier might agree to source their gas from another storage facility to save delivery costs. Often refineries will formulate competitor brands, with their additives, and deliver them to the stations. One tell tale, is if you see a late night unmarked truck deliver gas, it's probably not the name brand source.

.

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Response to raccoon (Original post)

Tue Feb 13, 2018, 08:01 PM

34. I don't know about my gas tank

But I'm always at least half full of gas myself as my wife can attest to.

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Response to ProudLib72 (Reply #34)

Tue Feb 13, 2018, 08:25 PM

38. You mean the venting doesn't help?

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Response to Wounded Bear (Reply #38)

Tue Feb 13, 2018, 08:29 PM

39. It's so I can roll coal on the tRumpers I pass!

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Response to raccoon (Original post)

Tue Feb 13, 2018, 08:03 PM

35. My a/c guy always told me to to shut off a/c

before shutting off engine and I would have less problems with a/c unit. Followed his advice and my 14 yr old car still cools perfectly.

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Response to raccoon (Original post)

Tue Feb 13, 2018, 08:07 PM

36. Yes in EARTHQUAKE COUNTRY

Hurricane country too I guess.

Power may be out for days, weeks, or in Trump's U.S.A, indefinitely ...

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Response to raccoon (Original post)

Tue Feb 13, 2018, 08:24 PM

37. If I could afford it, I would...

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Response to raccoon (Original post)

Tue Feb 13, 2018, 10:57 PM

40. I prefer to keep mine half empty

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Response to raccoon (Original post)

Tue Feb 13, 2018, 11:44 PM

41. That is how I roll

Whenever I get to the half way mark, I fill up. That is how I have managed my vehicles for most of my adult life. Don't have a reason for doing it other than fending off my fear of running out.

I was extremely poor for 20 years. The takeaway I picked up from that was to ensure I never run out of anything again like food or gas. Heck, I even get like that with the battery life on my Apple devices.

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