My friend says you should never let your gas go below 1/2 full because ...?

Question

it will cause dirt to get into your engine.. I don't agree. Who is right? You won't be penalized if you side with her. But, whatever you answer, please explaiin why.

(I think the only reason to fill your car often would be if you let it get close to empty, you could have a panic attack when you get the bill.)

Answer 1

your friend is misinformed. while there is always sediment in the tank, it will be picked up most often right after you have filled the tank as the incoming fuel stirs up the sediment. second, since most cars these days are fuel injected, they have a fuel return line to the tank, and that fuel will also stir up any sediment in the tank as the return fuel in under about 30psi pressure. thus since the sediment in the tank is pretty much always being stirred up, it gets into the fuel system anyway, and that is what fuel filters are for, and why they need changing on a regular basis. that said as indicated the fuel in the tank cools the fuel pump, so you dont want the fuel level to go below 1/8 of a tank on a regular basis.

Answer 2

Its more like 1/4 of a tank. When you let the fuel level drop below 1/4 of a tank your fuel pump will start sucking sludge off the bottom of the tank. Plus the fuel pump is partially kept cool by the fuel in the tank once the fuel level drops the pump will start to overheat, and there's where your huge repair bill comes in is when you burn up the fuel pump and plug up the fuel filter(s). Because the electric/electronic fuel pumps can get quite expensive.

Plus you shouldn't drive around until your on empty anyhow, and risk being stranded somewhere because you ran out of gas.

You will have a bigger panic attack after you get the repair bill for running low on fuel and burning up the fuel pump.

It won't cost you as much to fill up the tank if you don't drain it completely.

Answer 3

The fuel pump relies on fuel to keep it cool. It also doesn't have to work as hard if it is covered up with fuel. That is the only reason I can think of to keep it full. If there is any dirt in the tank it will always be on the bottom of the tank. The fuel pump pickup tube has a screen on it and is about 1-2 inches off the bottom anyway.

Answer 4

For the record: I never pursued an old woman friend who is or is not my junior. Fathers usually disappear after they make a wet spot on the sheets. Age difference does matter if you are both Seniors (one being a high school senior and the other being over 65+) Babbies are best kept in a warm cabbage leaf, hats are usually not necessary unless he is also bald. Bald babbies usually have self-esteem issues so he will need to join the toupee of the month club. Talk to the Donald about that. Gas costes lots more than fipty buck dollars. You should make that young woman split the cost and also take you out to McDonald's for the wear and tear. You should never marry a junior woman just for her babby making skills. She should also be capable of wielding a mean spatula in the kitchen (if you know what I mean) I have no idea about what your question really means. I always thought Geeks were neutered or Italian or something like that.

Answer 5

When you run your tank lower than half, it will start 'sucking' the fuel that is left and therefore tend to use the dirt that is left on the bottom of the tank. That is not going to happen often, unless you live in a VERY dusty area or are getting gas from a 'bad' gas station. It is not because dirt will get into your engine necessarily. It is due to the sensors being 'tuned' to a more than half full tank. In newer cars they have emission sensors/devices that depend heavily on what in going on in the fuel tank, and vapor lines. For example, if you leave your gas cap even a little loose, it will set off the check engine light.
In newer cars, it is recommended that you don't let it get less than half a tank on a normal basis.
He is right.
sorry.

Answer 6

I've heard the opposite. I've heard that if you fill up too much it causes some gas to sit, get old, and is bad for the engine.

Who knows? I used to not let the tank dip past half-full, only because I think ahead like that, and the tank ain't getting any fuller!

Still, now that gas prices are so high, I only fill up as a last resort. I also don't usually "fill 'er up," I just put in a few dollars here and there.

Answer 7

do you not think that what ever is in the tank no matter how full it is will make its way to the fuel pump ?you drive and the gas is constantly moving and so is the "dirt" in the tank .. then you have to realize if you never drive with lower levels of gas that its alot more weight in the car and less mpg so it costs you more to drive .. now think about this the fuel pump has a filter on the bottom of it and then there is another filter after the pump ... and all gas pumps now have filters on them too.. just get gas when you want

Answer 8

it wouldn't get into your engine. but if you ran the tank really dry then you could pick up some of the rust and dirt that builds up in the bottom of the tank. that stuff could clog your fuel filter and either leave you stranded or burn out your fuel pump and leave you with an expensive repair. It's ok to run it down to the last couple of gallons. just do all your maintenance and change your fuel filter every 50-100,000 miles

Answer 9

Some of the answers are kinda right and some are totally wrong, but the 1/2 tank concept is based on two major facts that I'll answer after dispelling a few "old wives tales".

1. Since water, crud, dirt, and rust are all heavier than gasoline and will naturally settle to the bottom of the tank, the fuel intake line does NOT go all the way to the bottom of the tank. This gives a good "buffer zone" to keep a certain amount of natural crud accumulation from being pulled into the fuel line. Even at that, the intake line also has a filter screen at the end to prevent large chunks of debris or rust from being sucked up when you hit a hard bump that tends to churn up stuff off the bottom of the tank. Since most gas tanks also have many internal baffle plates to keep the gas from sloshing around when you're diving like a maniac, the level of gas in the tank won't make any difference in your chances of sucking up anything from the bottom of the tank.

2. Unless you have a classic or antique car, everything else will have an electric fuel pump that either works intermittently on a pressure-demand basis or runs all the time in a pressure-regulated recycle mode. In either case, the pump will be more than adequate to supply sufficient fuel pressure to the engine regardless of how much gas is in the tank.

3. Problems start to happen when enough water accumulates in the bottom of the tank that it fills up that natural "buffer zone" and is at the same level as the fuel intake line. Now, each little bump or minor slosh will cause some water to be sucked into the line - along with any debris or rust that may be floating on the surface of the water (but too heavy to float on the surface of the gasoline). When you've reached this point, there is a problem because the little bit of water in the fuel will decrease engine performance and freeze the fuel pump, fuel lines, or fuel injectors in the winter (as already mentioned). Additionally, any debris or small rust particles (that are much easier stirred up by the heavier water) will be carried along with the water and start clogging the fuel-intake line's filter screen and your other inline fuel filters - which will eventually clog, stall the engine, and put you in walking mode (also known as "riding your Nike's").

Most people don't realize that every automotive fuel tank actually "breathes" in and out with each night and day. During the day, the tank and fuel normally heats up from higher daytime temperature - then heats up even more from road and exhaust system heat when you're driving. This causes the air in the tank to expand and become less dense (meaning it will hold less moisture); the expanding air creates internal tank pressure which is vented off through the tank's fuel vent system - but leaving the moisture behind in the tank. At night, everything cools off, the air in the tank contracts and creates a partial vacuum in the tank which pulls in cool, moisture laden, more dense air back into the tank through the vent system. The next morning the process repeats itself with the warm air venting out of the tank and leaving another bit of moisture behind. This continual "breathing" process eventually keeps raising the water level in the bottom of the gas tank - so:

1. Keeping the tank 1/2 full or more (especially before parking at night) means there's less air in the tank which will leave much less moisture behind the next day - thus greatly slowing down the process of water accumulation. Even though many gas stations have fuel filters on the pump hose, 95% of the crap that builds up in your gas tank is from internal rust constantly flaking off that is caused by the water at the bottom of the tank or moisture vapor filling the air space in the tank. So, less air in the tank means less water accumulation - which also means less rust accumulation with time. Some intelligent auto makers put a little drain plug in the bottom of the tank so it can be peridocally removed to drain out any water and crud that's built up over time and restore your "buffer zone" at the bottom of the tank.

2. However, the most important reason for staying at 1/2 tank or more is simply "Murphy's Law" that states you're most likely to have a major emergency that requires desperate and immediate transportation when the gas gauge is sitting on "E". This sorta equates to the same logic as not having your seat belt fastened at the instant you're really going to need it.

Perhaps this is not the answer you wanted to hear, but now you can be one-up on your friend by blowing him/her away with your vast knowledge about gas tanks that you probably weren't much interested in anyway :-)

Answer 10

your friend is WRONG! Dirt will not get into your ngine because of your gas level.There are many filters between the tank and the engine to prevent debris from getting to your engine. I have heard that only filling your tank half way will yeild better mielage in the long run due to the less weight of a half tank compared to a full tank... seeing as how gas weighs about 8lbs a gallon, this would seem to make sence, besides who can afford to buy a full tank these days?