Fill' er up


I have gotten in the habit of never letting my gas tank get below 1/2 tank. Usually between 1/4 and 1/2 I’m popping in to top off my tank. I have a brother in law who seems to know everything about everything. Or he thinks he does. He says that is not a good idea. That every so often I should let my tank register "EMPTY’. Something about junk or sludge always remaining on the bottom of the tank and never surfacing. Sounds kind of dumb to me. I continue doing the way I’m doing until I get an answer from you guys.


You are correct in my opinion. In new cars, the pump in the tank pumps from the bottom of the tank. In older cars without fuel injection, the tube through which the gasoline is sucked up by the fuel pump extends to the bottom of the tank. In other words, no matter what you drive, the gasoline that is delivered to the engine comes from the bottom of the tank. Running the tank down to empty serves no useful purpose. Besides, the normal motion of the car stirrs up the gasoline anyway.


He’s wrong. A fuel pump is typically inside the fuel tank and and sits very low…to provide the most fuel mileage.
There should not be any “sludge” in your fuel tank unless its been contaminted by an outside source. Any debris in the tank stay out of the fuel pump by a screen attachted to the base of the pump.
Keeping your fuel tank always with a 1/2 is actually a good thing. fuel pumps are cooled by the gasoline. people that let there tanks go to empty all the time are more probable to have a fuel pump failure by allowing there fuel pumps to run dry.


Neither one of you is truly correct but no one is wrong, either. This is one of those silly really-doesn’t-matter choices.

Continue doing things your own way if it gives you the most pleasure. Your method of trying to keep your tank at least half full is eccentric, unnecessary, and totally harmless.


I agree with this. If you needed a certain minimum depth of fuel in the tank to protect the fuel pump, it would be a simple matter for the mfr to calibrate the fuel gauge to accomplish this. Fill at “E” or before.


Ignore your brother inlaw.


Running out of gas is very costly. Avoiding running out is very wise.


The more fuel, the more weight you carry around, but I recommend carrying the extra weight. It may save the fuel pump.


im willing to take a guess here:

your sister is always yelling that he lets the tank get too low and wants your brother in law to pull over and get gas right?

ask him how many times in his life he has run OUT of gas. (once is too many times)

just keep doing what you do. BUT in the interest of family harmony, say thanks to him, for such a good idea, and you’ll do that the very next time you fill up.

if you (or your B I L) got crud in your gas tank it is because you/he bought gas a a cheapo gas station, and it has nothing to do with how low the tank gets.


I thought that running your tank down to almost empty left more room for water vapor and eventually rust particles. Also, that the water vapor would freeze the gas line in the cold weather. I keep my tank above 1/2 for convenience, in case I have an unexpected trip or something comes up.


Modern cars with evap systems don’t typically have this problem. The gas tank is part of a closed system with no venting to the air. The evap system will maintain a vacuum in the gas tank to prevent the release of hydro-carbons to the atmosphere. When parked, the tank will fill with gas vapors. I think since the early 90’s this has been the case. But I know since 1996, every vehicle made is this way.


I recall a caller a while back who had that question. Her husband fueled up less to save on fuel mileage. I’m fairly sure Tom & Ray said that the guy’s strategy was bunk.

Aside from mechanical issues. Why drive around with a quarter tank, especially if on a highway? Who knows if you will get stuck in traffic, or not be able to find a gas station?


Thanks for the info Bustedknuckles . . .I never knew that but it makes sense. Rocketman


Also, most vehicles today have fiberglass fuel tanks, so no more rust.