Victory

Fuel flowing through the pump is what cools the pump, not the fuel around it. You're at no risk of damaging the pump until you run completely dry, and even then, you're probably ok unless you keep trying to crank it over.

as far as debris and water, i don't think this is an issue in modern times. Gas additives prevent corrosion in the gas tank and most gas contains ethanol, which is highly hygroscopic. In fact, the gas line antifreeze additives you see on the shelf at the parts store for removing water from the gas are just straight denatured alcohol or methanol.

I always fill at between half an a quarter tank because if there's an emergency situation, you don't want to have to stop for gas. I got into that habit when I was a medic. Ambulances were supposed to be filled below half a tank under our policy.

Ca428

Yep, I understand the math, just don't like to depend on it. And really surprised the calibration of the meter/gauge is so far off.

When you fill up, do you stop at the first click (auto shut-off) of the gas pump or a few more?

NW_6MT

I think the gauge calibration issue is a Nissan thing. I had a Maxima prior to my G. Specs said same 20 gallon tank. Going well below 0 miles remaining lots of times and was never able to even put 18 gallons in it. High 17's was the max. The G seems to be the same. I've approached 0 remains a handful of times and always high 16 to low 17 gallons. This is completely topped off. Living in Oregon where it is illegal to pump our own gas (literally against the law and they will yell at you) I only get to experiment on road trips, but this has proven out dozens of times.
On the harmful side of things, that's just ludicrous. Put gas in whenever you'd like.

Selym

You're correct; ethanol is hygroscopic. That means it absorbs water from the air, which is a bad thing.

Gas line antifreeze typically contains isopropanol, which sequesters the water.

Ca428

I've NEVER had a problem with my tank picking up crap when running it low. From the days when I had a 1979 Ford Fiesta to today, I've always run my tanks low, sometimes dry and no problem with a fuel pump in any car I've owned, never replaced one. That includes two Acuras, 192k on one, 290k on another. I've NEVER used Heet or any other gas line antifreeze either, and I've owned cars in the last 32 or so midwest winters. Don't forget, the fuel system is essentially closed or nearly so, so no moisture from air should get in.

Ca428

Hmmmm, interesting that it's a Nissan thing. Didn't know Oregon is a full-serve gas station state, New Jersey is like that too.

Victory

Ethanol serves the same function as methanol or isopropyl. The hydroxyl group forms a polar bond with the oxygen in the water molecule. Doesn't matter what kind of alcohol it is, the chemistry here is the same. They all absorb water from the air.

Phase separation, which is the bad thing you are worried about, is not going to be an issue in a modern vehicles sealed gas tank. Assuming 80 degrees and 100% humidity, each gallon of 10% ethanol blend can hold the moisture of roughly 300 gallons of air before phase separation

emerilnut

I always stop at the auto shut off.

BigGrizzDipper

We were in my wife's '11 Murano (20 gal tank, 3.5L 6 engine) was at 0 and went another several miles before a station and needed about 18.8, so had about a gallon or so left after driving on 0 for a bit. I own a G but the murano powertrain is similar

blnewt

iTrader: (13)

5 years and still going strong, #whatathread! #shametheopisbanned

Ca428

Hmmmm, must be an oddball Nissan issue with an over abundance of caution to prevent from running out of fuel. Guess I'll have to do the math, see what my average mpg is and multiply by 20, then dial that number back a bit to be safe on a true range.

Black Betty

iTrader: (60)

So has anyone posting in this revived thread removed and examined the pump or looked around inside of their tank? I have. Multiple times. Maybe your experience differs from mine. I live in an area that requires 10% ethanol in gasoline. What I discovered was shocking.

No corrosion.
No water/sediment/trash/foreign particles floating or settled inside the tank, even after using many non Top-Tier fuel stations. None. Just gas.
The fuel pump floats in cold gasoline and has cold gasoline flowing through it. The only way I can see that it would "burn up" or "suck up air" is if the car is run COMPLETELY empty of fuel and then the driver attempts to continue to start and run it repeatedly.
I have run out of fuel in my G37. I didn't attempt to restart the car with the tank empty. I refilled it with 1.5 gallons of fuel. It started immediately (allow the fuel pump several seconds to pump fuel to the injectors before starting - you can hear it when you turn the ignition to on) and proceeded to the next station where I filled it up. Ran fine.

Black Betty

iTrader: (60)

Every manufacturer has fuel gauges that show empty before the tank is completely empty. Some more than others. The computer that calculates it is not completely accurate and is influenced by a number of factors so there isn't a precise amount of reserve capacity that you can rely on. My experience has been no less than 2 gallons and as much as 3 when the distance to empty reads zero. Yours may differ.

Ca428

I started this thread to focus on the amount left in the tank when the warning light comes on and/or the needle is on E. Thanks for everyone's comments, good to know your car started right away after running it dry.

emerilnut

Now I'm wanting to hear the story of how the OP got banned.