I've pushed mine to 0 mile till empty once or twice. I always wait till at least 25 miles till empty to fill up. It's very true that any moisture will collect in the bottom of the tank but what's the best way to avoid that? By using all or most of your fuel everytime. To me, leaving the same 8-10 gallons in the bottom is asking for trouble more.

And OP, you may be expecting too much. Err on the side of caution if you're not sure where the next station is. My DTE is wacky at times.

 

Put 1 gallon of gas in a 36 gallon tank and you get the picture. Remember this is a long flat tank and that you are driving so fuel moves around and sloshes back and forth. Just because the truck stays running don't mean the fuel pump is not picking up air gulps.


For comparison... take your hot water tank in your house, roughly 40 gallons... lay it on the side and add one gallon of water...

 

A single can of dry gas will do the same with little to no risk to your injectors. Remember that WATER is not compressible and can do a number on your injectors. No reason to run a tank that low unless it's an emergency thing. Do it enough and you will for sure be replacing a fuel pump… it's just a matter of time imo.

 

With ethanol oxygenated gasoline (10%), water up to at least 1% is readily kept in solution with the gasoline. Running e85, I'd guess that you could mix much higer amounts without separation, though it will not run very well!

With no separation the water passes through the engine with no problems in general, though power is decreased. It is only a problem when allowed to separate. And if you are getting more than 1% water with your gas you need to have a talk with your gas station!

If it has not separated, running the tank lower will have minimal effect on the total % of water in the tank (the water % between the old gas vs refilled gas should be minimal). If it has separated, running it low will cause major problems.

Of course, if you are able to get ethanol free gas, none of this applies since very little water will dissolve in ethanol free gas.

 

Interesting that I noticed this thread today. I am at 35km to go according to DTE. Around 22 miles for my American friends. However, according to my trip computer (which I reset at every fill up), I have only used 120L of my 136L tank. So based on my current winter MPG I should have just under 100km not 35km to empty.

So what do I trust. DTE gauge or my Litres used reading on the trip computer?

 

I try not to use more than half a tank before I fill up again, too painful to watch that gas pump counter.

I have had my DTE down to around 70 miles, but that was as low as I've ever gotten and that was on a trip from MD to Central Florida.

 

Yep, I don't worry about moisture buildup but I was just pointing out that if it was an issue, leaving a certain amount of fuel may not be the solution. Maybe it is and I'm doing it wrong. Either way, I didn't buy a truck with a 36 gallon tank to use 26 gallons. What about the guys with the 26 gallon tank? Are you leaving 10 gallons in it? I get 15mpg, 16 gallons would give me 240 miles of range. I'd fill up every other day. Ugh.

 

I've run mine pretty low a few times on long trips. I think the DTE number is accurate.. maybe a bit conservative, which is good. 2013 XLT, 36 gal tank.

 

I regularly run mine down to 0 DTE. Every time I do I can only fit 31-32 gallons back in the tank. On the 36 gallon tank, I am fairly certain that the computer takes into account a 5 gallon reserve. So when it says zero, you really still have a reserve. My experience definitely backs this up.

This is of course contrary to my flight training fueling. There you fill up to max everytime you come back to land to avoid moisture building in the tank. Of course, in that scenario, getting water in the engine at 6500 feet can be deadly. Here, not so much.

 

Fuel tanks don't have a hole in the bottom allowing them to completely empty out. there is a strainer suction tube into the pump that sits "close" to the bottom of the tank... Put four gallons of water in your bathtub and see how deep it is