The best video I found to explain why synthetic is better than conventional (for those of us that want to keep our cars a long time) is by YouTuber EngineeringExplained and titled "Is Synthetic Motor Oil Better For Your Car?" if the link i copied works its here:
I would follow the manual because there are millions of hours of thought, experimentation, testing, and examination by some very highly trained technical people that contributed to it. Legal added thier conservative liability based view to it. And marketing was only allowed to do the cover, thank me for purchasing a Ford product, and occasionally suggest that I buy the Ford version of whatever I may need or want.
I would follow the manual because there are millions of hours of thought, experimentation, testing, and examination by some very highly trained technical people that contributed to it. Legal added thier conservative liability based view to it. And marketing was only allowed to do the cover, thank me for purchasing a Ford product, and occasionally suggest that I buy the Ford version of whatever I may need or want.