I recently purchased a 2007 Fat Boy. I'm about to do a 10,000 mile oil change and wanted some opinions. I'm looking at using either the Lucas 20w50 synthetic motorcycle or the Mobil 1 V-Twin oils in the engine. Then either the lucas or mobil 1 75w/90 gear oil for the tranny. My real question is what to use in the primary. I've read that the HD F+ is a good choice, but I want to know if I can use the Mobil 1 Racing 4T 10w40 in it without any problems and is it a good choice? I understand from Mobil's site it there is no friction modifiers in it, which is good for the primary.