According to the 1999 Ford F-250 Super Duty Owner Guide :
With engine oil filter change :
The 6.8 liter V10 gasoline engine takes :
( 6.0 U.S. quarts of 5W-30 )
The gas tank on the 2010 Ford F-450-Super-DUTY holds 38.0 gal..
The gas tank on the 2011 Ford F-250-Super-DUTY holds 35.0 gal..
The gas tank on the 2007 Ford F-350-Super-DUTY holds 38.0 gal..
The gas tank on the 2014 Ford F-350-Super-DUTY holds 35.0 gal..
The gas tank on the 2003 Ford F-350-Super-DUTY holds 38 gal..
The gas tank on the 2002 Ford F-250-Super-DUTY holds 38 gal..
The gas tank on the 2011 Ford F-450-Super-DUTY holds 37.5 gal..
The gas tank on the 2013 Ford F-350-Super-DUTY holds 35.0 gal..
The gas tank on the 2009 Ford F-350-Super-DUTY holds 38.0 gal..
The gas tank on the 2004 Ford F-350-Super-DUTY holds 38 gal..
The gas tank on the 2001 Ford F-250-Super-DUTY holds 38 gal..
The gas tank on the 2006 Ford F-250-Super-DUTY holds 38 gal..