Synthetic Oil - good or bad?

Boy did this thread take a sharp turn!

I'll try to get on track again. I use synthetic in a new car that requires it, in the engine.
I use dino diesel, cause thats what it was designed to use (and i dont like $150 oil changes.)
I use dino in my old cars and race cars. I change it often enough to keep them clean.
I dont use synthetic of any sort, in my trans or rear ends. Too much advice from pro's in the field, and personal experience, specifically not to use synthetic. There have been literally trillions of miles travelled on dino gear oil and trans fluid, i see no need to change.