It's in your owner's manual. If you don't have the paper copy anymore, you can download a copy from www.fleet.ford.com
under the heading of MAINTENANCE.
If your original owner's manual is missing, download a soft copy from www.fleet.ford.com
under the MAINTENANCE tab.
1994 Taurus SHO 3.2/ATX - Gone
1989 Taurus SHO What a project! Retired at 249K.
1997 Ford F150 SC 5.4L - Gone
1998 Ford Contour Wifey's old daily driver, now mine.
2007 Mercury Mariner AWD - Wifey's newdaily driver