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Running gas tank to empty

You recommended that the caller convince her husband NOT to run the gas tank down. Most importantly, especially with a new baby, getting stuck is inconvenient and possibly dangerous. Yes, that is good advice, but you didn’t give reasons why it may damage the car. One very good reason is related to their location. Living in New Hampshire it gets quite cold in winter. Having a very empty gas tank leaves a lot of room above the fuel for air. When it gets cold at night, the water vapor may condense. That water will eventually build up and possibly form an ice dam in the fuel line.

If this hubby wants a bit of excitement in his life wait until the expectant wife needs to deliver her kiddo at 3 am when the ‘low fuel’ lights are twinkling. There’s no way on God’s green earth that he’ll survive the experience, especially if the choices of all-night stations is limited. Mom will have two words for him, one of which will be ‘you’.

If the tank is empty my car is worthless.

@757guy
Yes, some folks get their highs from driving on vapors. We’ve had a number of posts on this subject and everyone agrees that this practice is foolish and can be dangrous.

The condensation part is real in cold climates, although today’s fuels often have ethanol in them, which absorbs water. In hot areas, an near empty tank puts a lot of stress on the fuel pump.

In any case, when th fuel light comes on you should immediately gas up; then when you get home, look at the gas tank volume in the owner’s manual. Mine goes on when I have about 3 gallons left, but that may change as the car ages.

This forum is great! We have a caller whose husband wants to see how low he can let the gasoline become in the tank and have the car still keep going and a poster who has been experimenting since 1984 with driving cars without changing the oil to see if the engine will fail. This leads me to believe that I have been far too cautious in my life: 1) I start looking for a gas station when my gauge indicates I have about 1/4 of a tank left; 2) I change the oil according to the severe use in the owner’s manual; 3) I never let my beer supply in the refrigerator go lower than 5 bottles. I may begin living dangerously as far as 1 & 2 are concerned, but I think I’ll still stay with my restocking value on the beer.

Maybe my dad gave me booogus advice, but he always told me not to let my gas level get too low because the fuel pump will ingest sediment at the bottom of the tank and that can ruin the fuel injectors. He could be way off the mark with that theory, but it makes sense that a full gas tank will dilute any impurities in the fuel more than an empty tank.
Whether my dad was right or wrong, I agree with Click and Clack that the caller’s husband needs to get his excitement somewhere else. Maybe he’s just a cheapskate and doesn’t want to fill up every time he stops at the pump. Whatever his reason he needs to be better prepared for that baby!

I seem to remember Click and Clack saying that fuel in the tank keeps the fuel pump cool, so running around on fumes might lead to premature failure.

It doesn’t cost any more to keep a tank full than it does to keep it empty.

You don’t need to worry about ingesting sediment when the fuel in your tank is low. But the moment your fuel pump begins sucking air, rather than fuel, you’ve lost the “cooling effect” of the fuel, which is essential to the life of the pump.

This forum has had several long threads on this subject.

There is just not anything to gain by letting it run low. The additional fuel used to make a less convenient trip at the last minute far out weighs any fuel saved by having a slightly less weight due to less fuel.

I guess if you want to carry this to a conclusion you should never fill your tank, only add just enough to get to the next fuel station.

“There is just not anything to gain by letting it run low.”

Actually, there is something to gain - time. If I fill my tank when it’s down by half, I fill it twice as often. I have to find a cheap gas station on line, drive there, and fill up twice as often as I do now. I have other ways to spend that half hour. I almost always get gas before the dreaded yellow reminder glows, but I fill up as soon as I get to the Cheap Zone if the E-reminder lights up. Fortunately, the cheapest gas in town is usually near work and on the way home.

I am a paralegal at the Rose Barracks Law Center near Vilseck, Germany. We prosecuted a Soldier for causing an accident in which he pulled into traffic with what seemed like plenty of space, but his car ran out of gas at that exact moment, stalled in the middle of the street and caused another car to crash into his. He was prosecuted for violating Article 111 of the UCMJ, Reckless Driving. Further, he was held personally liable for the injuries and damage. After he was prosecuted, fined, reduced in grade and deprived of his liberties, he was sued.

I have also been on road trips in which I run the car to near empty, pull into a gas station for a fill-up, only to learn that the station is closed. Gas in the tank is like toilet paper. It’s better to have it and not need it than to need it and not have it.

“It doesn’t cost any more to keep a tank full than it does to keep it empty.”

Not only does it cost no more, it may actually cost less. With the ever-increasing price of gas, if I fill my tank today at…let’s say…$3.29 per gallon, I would actually spend less money than if I waited an extra couple of days and filled the tank with gas that had increased in price to…perhaps…$3.35 per gallon. Yes, I know that the difference in price for that one fill-up is not significant, but–when totaled over the course of a year or more, then the price advantage for filling up a bit sooner begins to mount up.

On this topic–more or less–many years ago, I had a boss who would only buy $5.00 worth of gas at a time for his Buick LeSabre. Yes, gas was much cheaper then (in the '80s), but his car was not exactly an economy champ. The result was that he wound up going to the gas station about 4 times per week.

I tried explaining to him that he was wasting an incredible amount of time with about 3 extra visits to the gas station each week, and his answer was something along the lines of…but this way they can’t cheat me. I asked him to explain this theory of his, and he could not really verbalize it beyond giving some vague statement about…if I tell them to fill the tank, I have no idea of whether the total number of gallons is correct, and they might be charging me for more gas than I need. Yes, he was a very strange man.

If my gas tank is full…
it has doubled in value :wink:

The cheaper the car, the greater the increase. A worthless car would be infinitely more valuable.

I will let my gas gauge get down to 1/4 before I start thinking about getting gas. On rare occasions the low gas light has come on and I will fill ASAP if it ever got to that point. I don’t like to make daily stops for gas so I go to 1/4 or less just to reduce the number of stops for gas.

Tom and Ray did mention that letting the tank get too low is bad for an in-tank fuel pump, which uses gasoline as coolant/lubricant.

There is something to be said about saving gas by not hauling as much of it around, but the savings will be minimal, and I wouldn’t do it like the caller’s husband is doing it. If you have a 20 gallon tank and refill it when it half empty, you continuously haul around 10 gallons of gas you aren’t using. For day-to-day commuting, I wait for my tank to get down to about 1/8 of a tank, and I fill it to the halfway mark. The only time I fill it all the way is when I am on a longer trip. I might not be saving enough gas for most people to think it’s worth it, but I like knowing I am doing every little bit I can, especially since there are several gas stations along my commute I can stop at with hardly any inconvenience.

Tom and Ray did mention that letting the tank get too low is bad for an in-tank fuel pump, which uses gasoline as coolant/lubricant.

No, they said they thought that.

Name one person who has needed to replace a fuel pump because of running out of gas.

Running low on gas won’t hurt a pump. Running low enough on gas to where the engine is bucking due to air being inhaled will damage a pump.
This does not mean the pump will die the first time it happens. It’s cumulative. Those fuel injection pumps are screaming RPM-wise and it doesn’t take very many seconds of dry bushings, dry brushes, and dry armature commutator for damage to occur.

Take a known good pump, connect it to a battery source, and then note how long it lasts while running dry.

Maybe there are reasons why car makers make inaccurate gas gauges …OP’s husband is just one of them.