According to the 2005 Ford Mustang Owner Guide :
With engine oil filter change :
The 4.0 liter SOHC , V6 engine takes :
( 5.0 U.S. quarts of 5W-30 )
Six quarts
The gas tank on the 2005 Ford Mustang holds 16.0 gal..
I believe that is almost 3 quarts
6 quarts
Automatic takes 11.9 quarts Manual takes 2.75 quarts
( 5 quarts ) with engine oil filter change , according to the Owner Guide
According to the 2003 Ford Mustang Owner Guide : For the 3.8 liter V6 engine : With engine oil filter change : ( 5.0 US. quarts of 5W-20 engine oil )
16.0 Gallons
I believe that holds 5.6 pints ( so , not quite 3 quarts )
With engine oil filter change ( 5 quarts / 4.7 liters of engine oil )
The coolant capacity of the 2003 Ford Mustang GT with the 4.6 L - SOHC - V8 engine is : 13.3 liters / 14.1 quarts
I believe that takes 5 U.S. quarts with oil filter change