According to the 1999 Ford Mustang Owner Guide :
With engine oil filter change :
The 4.6 liter , SOHC , V8 engine takes :
( 5.0 U.S. quarts / 4.7 liters of 5W-30 )
That would depend on which engine you have and what year of Ford Mustang
The 2009 Ford Mustang's engine produces 240 ft-lbs. @ 3500 rpm.
The 2012 Ford Mustang's engine produces 280 ft-lbs. @ 4250 rpm.
The 2007 Ford Mustang's engine produces 240 ft-lbs. @ 3500 rpm.
The 2001 Ford Mustang's engine produces 225 ft-lbs. @ 2800 rpm.
The 2004 Ford Mustang's engine produces 220 ft-lbs. @ 2750 rpm.
The 2002 Ford Mustang's engine produces 220 ft-lbs. @ 2750 rpm.
The 2010 Ford Mustang's engine produces 240 ft-lbs. @ 3500 rpm.
The 2005 Ford Mustang's engine produces 240 ft-lbs. @ 3500 rpm.
The 2006 Ford Mustang's engine produces 240 ft-lbs. @ 3500 rpm.
The 2014 Ford Mustang's engine produces 280 ft-lbs. @ 4250 rpm.
The 2008 Ford Mustang's engine produces 240 ft-lbs. @ 3500 rpm.