I read that the most efficient oil for the Northstar and other newer engines is GF3 rated oils.
Mobil One is rated at GF2 while some blends and non-synthetic oils are rated at GF3.
I have been using a blend of synthetic and non-synthetic oil rated at GF3.
I don't know which is better for the Northstar.
The Factory recomends 5W-20/30 oil.
Is it possible that the thin side of this oil (5 W) causes Northstars to burn or leak oil more rapidly?