engine oil & quantity 6.1

Not sure about the 6.1, but I believe the 5.7 calls for 5w20. If the 6.1 is the same I really wouldn't run thicker... I would be worried about improper/poor lubrication, as well as power loss from thicker oil.

I think i remember that the capacity of the milodon pan is less than factory for clearance. I don't remember specifically, so it may be worth a call to them...