I know Amsoil well but stopped using it long ago. Personally, I use Mobil-1 Synthetic 0W30 btw, as I do use it in Winter and I want that oil on the valves ASAP, especially when we have real cold. After 50 hours a bit brown is OK and you probably could still see through it. If that was the 1st oil change (after the short 5 hour breakin one) that is not unusual.
TIP:
It's easier to drain the oil out of that genny if you have it up off the ground so that stupid drain tube actually clears the lip of the cover. After 2 messes, lesson learned. I think they could have improved on that drain setup but I've seen much worse too.
No complaints otherwise my Champion 4650 has indeed been a Champion.
I ended up putting the generator on 4 x 4’s… just enough to clear the drain pan. Bit of a pain, I agree. Drain tube could have been a wee bit longer.