Greetings Alan,
WOW you have asked a loaded question. You will find many conversions about what is the best oil and filters and some people have very strong opinions.
Myself, I just have my Bullitt serviced by the dealer who uses Motocraft synthic blend 5W20. Luckly, I have a very good and dependable local dealer. Just make sure to use a good brand of oil either a synthic blend or full synthic. Hopefully you have read the owner's manual. Use 5W20...do not let someone talk you into 5W30 or worse, 10W30. Also the recommended oil change interval is 7500 miles for normal service or 5000 miles for severe service. My personal opinion is no more then 5000 miles. For most people 3,000 miles or less is a waste unless it is subject to "severe service" as defined in the owner's manual.
Just my 2 cents worth (worth about a penny these days).
Drive and Enjoy your Bullitt.