Hey so i just went and got my first oil change with the new engine and opted for the non synthetic (i heard that its better on break in, even though i already have 1600 miles on the motor i figured it couldnt hurt to be careful)

are there any advantages to non synthetic over synthetic, or is synthetic still better?

 

What was in it in the first place? And I am confused is this engine working fine?

 

i had synthetic in it before...
and i had a new engine dropped in sicne my other one died..

 

How long is the suggested break in period?

 

1500miles

 

Nothing to worry about. Is this a stock factory replacement? If it is you are good to go. If it is an older style non roller motor The manufactorer may recomend break in with regular just becouse it tends to have more zddp and boron in it than synthetic.
It came with synthetic though so I would not worry about it.