Our fuel tanks are supposed to be 28 gallons. The most that I have ever put into the tank at once is 25.2 gallons. That is with the low-fuel light being on for about 35 miles and the needle at the bottom "leg" of the E.

Also, I went 392 miles on that tank. I would like to go another 1-2 gallons if possible and get 414 miles on a tank.

I was wondering what the most you have had to put in at once was?
:)

Never tried to run it that low. If the MPG screen says that I have "*" miles left, I fill up. :)

On an another note, what synthetic diff fluids are you using? Anything synthetic in the transmission?

I put 420 on her one time, ended up putting 27.5 gallons in. A little too close for my taste, but I have noticed you can run a bit while it's buried on the E. Reserve seems to kick in with around 5 gallons left.

I let my fuel level run low one time, and put in 27.2 gallons. I usually never let the level drop below 1/4 tank, but it's good to know you can use that much from the tank if you need to.