The simple answer is that it is worth what you can get for it.
Depending on the following items and more: your location, miles on the vehicle, condition of the vehicle, equipment on the vehicle. It also depends on: whether you are trading the vehicle to a dealer, selling it to another party yourself or the price a dealer puts on the window when selling.
Several websites attempt to address this type of question. One reliable source is Kelly Blue Book (kbb.com).
my 2000 Lincoln navigator weighs 6700 lbs.
A 2000 Lincoln Navigator needs 6 quarts of oil, and the recommended viscosity is 5W20. ========================================================= The 2000 Lincoln Navigator Owner Guide shows to use ( 5W-30 ) The 6.0 U.S. quarts with engine oil filter change is correct
A ( 2007 ) Lincoln Navigator is 106 liters / 28 U.S. gallons
$20.000
The 2004 Lincoln Navigator's engine produces 355 ft-lbs. @ 2750 rpm.
The 2008 Lincoln Navigator's engine produces 365 ft-lbs. @ 3750 rpm.
The 2002 Lincoln Navigator's engine produces 355 ft-lbs. @ 2750 rpm.
The 2011 Lincoln Navigator's engine produces 365 ft-lbs. @ 3600 rpm.
The 2010 Lincoln Navigator's engine produces 365 ft-lbs. @ 3600 rpm.
The 2007 Lincoln Navigator's engine produces 365 ft-lbs. @ 3750 rpm.
The 2003 Lincoln Navigator's engine produces 355 ft-lbs. @ 2750 rpm.
The 2009 Lincoln Navigator's engine produces 365 ft-lbs. @ 3600 rpm.