BS, like the trash in the fuel from the local exxon etcetc

every vehicle I have I usually let go till the fuel light cuts on , and have coasted in a few times on fumes w/o issue


ditto the gas tanks in the ground,
unless you are buying gas from some old station that has not be updated or still has the tanks from 1958

all modern stations have sensors in the tank to tell them how much water is in the bottom (there is and always will be) and most delivery drivers have a measuring stick and use a paste on it that turns color when it hit water, so the drop it inm pull it up and check the depth (almost always the same as the sensors say, and well below the pickup,

and, the old 'don't buy gas if they just got a delivery is BS, due to the filters the fuel goes thru before it gets to your tank

Personally, I don't allow that. But not for the sediment or other concerns; I ran out of gas alongside I-26 in Charleston, SC once, and had less than a dollar on me. Gauge wasn't quite reading empty, but it was. Even with the gizmos now saying I have X miles remaining, I gas up at about the quarter full mark at the least.

I had always filled up at 1/4 tank because I had a job with an emergency response component to it. My old 2001 Silverado a 1/4 tank was 100 miles.

My buddy's Silverado fuel pump died at 60k miles but mine made it to 107k. The owner and head mechanic at my neighborhood independent shop said 107k was rare so keep doing what you're doing.

18 or 19 years later, the only thing I've changed on filling up at 1/4 tank is peak hurricane season (Sept 10 plus/minus 3 weeks) I fill up at 1/2 tank. The run on gas stations is real when hurricane enters GoA and if a hurricane hits gas stations with power have multi-hour waits.

Yep.

Filling around the 1/4 is smart practice.

If you ever need to evacuate on short notice depending on the threats in your location, wildfire, flooding, chemical spill, hurricane.

Having the ability to move about 100 miles, gives you a better chance of getting beyond the danger, even if you run out of fuel, you are at most, inconvenienced for a short amount of time, but you will be able to get fuel eventually.

Trying to find fuel in the moment on a near empty tank, not so much.

@.38supersig covered the pump issue.

The way I heard it was that a low fuel level increased the chances of getting water in the fuel from condensation. The water would lead to rust and corrosion. Therefore better to keep it full. Sounds vaguely logical, but I'd need to see some experimental confirmation before buying it wholesale. I usually try to keep tanks relatively topped up "just in case." Never worried about wearing out the pump or rusting out the tank from the inside.

I'll vote "myth." Perhaps even promulgated by fuel sellers.

Half has always been the new empty for me for as long as I can remember. For years I thought it was illegal for women to pump gas. My wife and daughters vehicles were always close to empty. Then one day I saw a woman pumping gas. It was a revelation to me.

Myth.... at least Google thinks so... much of which has been said here, modern fuel pumps are encased in an area that has fuel even when you run the tank down very low. The sediment claim is BS, because all fuel tanks sit low enough in the tank that regardless of fuel level it would pickup any of it and regardless of the fuel level if you did have some in the tank it would either be suspended and ingested by the pump or slosh it around as you turned and stir it up...

The claim that dropping below a quarter tank of gas instantly ruins your fuel pump is largely a myth.

Modern fuel pumps sit inside an internal reservoir bucket that stays flooded with fuel even when your dashboard light turns on, meaning the pump stays cooled and lubricated during normal low-fuel driving.

The Truth Behind the Myth

The Sediment Fear: People say low fuel sucks up dirt from the bottom. In reality, the fuel pump always draws fuel from the very bottom of the tank anyway, whether it is full or empty.

The Real Danger: Your pump only faces actual risk if you make a heavy habit of running the car completely dry until the engine sputters and dies, which causes the pump to ingest air, overheat, and lose lubrication.

Occasional Dips: Letting your fuel dip near empty on rare occasions will not cause immediate, catastrophic failure

quote:

Originally posted by architect:
The way I heard it was that a low fuel level increased the chances of getting water in the fuel from condensation. The water would lead to rust and corrosion. Therefore better to keep it full. Sounds vaguely logical, but I'd need to see some experimental confirmation before buying it wholesale. I usually try to keep tanks relatively topped up "just in case." Never worried about wearing out the pump or rusting out the tank from the inside.

I'll vote "myth." Perhaps even promulgated by fuel sellers.

I imagine most tanks now are plastic, so rust is even less of an issue.

I like the 1/4 tank practice. If you've ever been followed it's good that you're not near empty if a perp fails to break off after a reasonable distance and repeated right hand turns. Good also for avoiding buying gas in sketchy neighborhoods. I've had to do that for waiting too long to refill, not a fun way to gas up. Then you have to do it twice, buy 5 bucks of gas to get the hell out of dodge, then fill up again getting back to safer territory.

My Dad was a mechanic and told us not to run our cars low on gas for this reason. Also to never fill up if the gas delivery tanker was at the station. Wait and go back later.

I always keep my gas tanks topped up. Here in Michigan, we often get weather related or traffic crash related stoppages on the freeway that neccessitate sitting at a standstill for hours, sometimes in sub-zero weather. In those situations, you don't want to be shitting your pants that you are about to run out of fuel.

I was once in a van pool. The other drivers would let the tank get almost empty before refueling. It was my habit to top up the tank every time it was my turn to drive.

One time on a particularly cold January day there was a fatal crash that required hours of police investigations, and traffic was re-routed to really rural back roads. A lot of sitting and waiting then crawling along bumper to bumper. We had to drive for hours to get back to our base, nary a gas station in sight.

One of the passengers looked at the gas gauge and said "Wow, we are really lucky we started out with a full tank!"

I just smiled.

quote:

The only thing I have ever heard of was on some F-150's with the 36 gallon gas tank. The fuel pump was at one end of the tank, and if you parked on a slope in the opposite direction and the tank was not over 1/4 full, it wouldn't start - all the gas was at the other end of the tank.

I can confirm this is true. Wife drives a 2017 F-150 (5.0 V8) with the 36 Gallon tank. Our driveway is on a slope. If she parks there (nose down) with a 1/4 tank or less, it won't start. I have drifted it to the street twice now, unpowered, then I let it sit for a minute it will now fire up (and I took it straight to the gas station). At this point I really don't let her get under 1/2 tank in her truck.

Back to the OP, I think its a fact. The fuel in the tank helps keep the pump cool.

I drove a `97 F250 diesel for 20 years. It had dual fuel tanks with a switch under the dashboard. I got into the habit of running until the tank I was on ran empty (or nearly so) and the engine started to sputter. Then I'd switch tanks and in a few seconds it was running fine again. Then in a day or two or three I'd fill up the empty tank.

My current truck, a `22 half-ton, has a 36 gallon tank in it. I don't usually let it get below half full, sometimes 1/4, before I top it up. As I get older I find myself leaning more toward 'better safe than sorry'. Also, I'm paying more attention to 'What if ISIS blows up a pipeline tomorrow and all the gas stations close?'

you have to really think car engineers are idiots if they would design a system that depends on a specific amount of fuel in the tank for the fuel pump to survive.
Running out of fuel has serious issues at a variety of levels, but low fuel simply does not.

When China or North Korea decide to shut down the grid to blackmail the US will you feel good about having a vehicle with a 1/4 of a tank of gas?

I worked in the dealership service department environment for many years. Chevrolet/GM if you were interested. Previous life & career. Master Certified ASE Technician, Auto & Light Truck.
One of the dirtiest, nastiest, worst, most unpleasant jobs for a service technician is replacing the in the fuel tank, electric fuel pump.

Here where I live, solidly in the "rust belt" and yes, that makes a huge difference. Rust debris, raining down on you getting the fuel tank out from under the vehicle. Gasoline/diesel up past the elbows.
What started as a relatively simple task of changing the electric fuel pump, turns into a massive can of worms.

The straps that hold the tank into the vehicle, when rusted, they break. And the parts department doesn't stock them, so you push the vehicle outside and wait for the new straps.
Sometimes, you can't disconnect the fittings where the pump connects to the fuel lines. You try and unscrew them, and you twist off the threaded ends on the fuel lines.
It isn't like you can break out the oxy-acetylene torch, and heat the threaded fuel line fittings! Everything is filled with flammable fuel!

And the parts department doesn't stock them, and you push the vehicle outside and wait for the new fuel lines.
Sometimes the factory replacement fuel pump has different wiring and connectors for connecting the new pump to the existing vehicle wiring. Then you are soldering/heat shrinking/remaking wiring.
I could go on for pages about the problems you can encounter changing electric fuel pumps that live inside the fuel tank, but I won't.
Some newer vehicles, the tank and lines are plastic, with less rust issues, but it isn't yet universal across all the makers yet.

What I can tell you is the FUEL PUMP inside the fuel tank, IS cooled by the fuel in the tank.
And I can tell you that the BUSHINGS on the electric motor in the electric fuel pump ARE lubricated by the fuel in the fuel tank.

So anything you can do as a driver/owner of a vehicle with an electric fuel pump mounted inside the fuel tank, something that can only increase the life span of that fuel pump, wouldn't you do it?
Myth? Half truth? Fact? You gamble, it's your vehicle and your wallet for the repair. I avoid below 1/4 tank when I can.
I'm not saying every single time don't run it below 1/4 tank, sometimes stuff happens and it just happens.
Me? I avoid running below 1/4 tank when ever humanly possible, just because I know exactly what can happen when the in tank fuel pump needs replacing. And I know the repair job will be mine.

[QUOTE]Originally posted by cee_Kamp:
I worked in the dealership service department environment for many years. Chevrolet/GM if you were interested. Previous life & career. Master Certified ASE Technician, Auto & Light Truck.
One of the dirtiest, nastiest, worst, most unpleasant jobs for a service technician is replacing the in the fuel tank, electric fuel pump.

Here where I live, solidly in the "rust belt" and yes, that makes a huge difference. Rust debris, raining down on you getting the fuel tank out from under the vehicle. Gasoline/diesel up past the elbows.
What started as a relatively simple task of changing the electric fuel pump, turns into a massive can of worms.
/QUOTE]

Master certified here also, Problem questions on vehicles in here on general questions...
People that did not turn wrenches do not understand how important vehicle year, Make and Model are.
Some reading this will think that the fuel pump in the tank of a older Camry wasn't that bad to do (cost wise) when they had it changed in the shop.
On those, many Subarus and probably the OP's car can be pulled by removing the back lower seat cushion.
The reason I mention this , there is no general answer to the fuel level question, some vehicles will play nice on a empty tank, some will not, fuel pump quality and design is a big factor.
But anyway, it does make for a good discusion.
I don't see any disadvantage to keeping it above a 1/4 tank, just "possible" problems running it lower.

Edit to Add:

I have a 08 Silverado ( gas engine).
This is where it gets interesting, '08 was the bailout year, some fuel pumps were Bosch and some were GM. My truck does not play nice on a low fuel tank with the GM pump. the owner of the truck with the Bosch pump will speak up and say, "I have no problems running it empty, do it all the time".
But someone will mention here that they got 300k miles out of their pump

This message has been edited. Last edited by: rizzle,

quote:

Originally posted by lyman:
BS, like the trash in the fuel from the local exxon etcetc

every vehicle I have I usually let go till the fuel light cuts on , and have coasted in a few times on fumes w/o issue


ditto the gas tanks in the ground,
unless you are buying gas from some old station that has not be updated or still has the tanks from 1958

So you never buy fuel from rural stations with older pumps, etc? I can tell you I was quite good friends with the owner of a performance shop locally. He specialized in turbocharged performance cars. He had thousands of blown motors in his shop to be rebuilt due to bad fuel. Shattered piston ring lands. Damaged rod bearings to name a few things. I guess if you live in neverland in some major city or suburb and only buy fuel at state of the art newer gas stations maybe. But many of us have to buy fuel from rural or very rural gas stations. There is no harm in hedging your bets and topping the fuel tank off at 1/2, 1/4, 1/8, etc, especially if it’s a rural gas station with older pumps. Bad fuel causes detonation and that is no bueno for your motor. Each to his own however. It’s not like the gas station charges you an extra fee or tax for topping off a fuel tank.

When I started driving, my dad advised me on many things. One recommendation was to keep the gas tank above the 1/4 tank level. His reasoning was that during cold weather the low level of gas could allow absorption of water vapor which would freeze in the fuel line. This was in the time of carburetors, mechanical fuel pumps and dry gas.
I follow the upside/downside principle, there is no downside to keeping the tank at least 1/4 full and I have followed my dad's advice for 55 years.

I have always filled up at about 1/4 tank. Gas is something you can’t do without and the time could come that you don’t have the opportunity to fuel and end up inconvenienced doing so or worse empty. Of course it makes a big difference when your mpg is closer to 10 than 30.