Just did my head gasket and while i had it running with the valve covers off, I noticed i'm not getting oil to the rockers on the back 3 cylinders. Now i do have a really thin oil in it right now.Bought the cheapest crap i could find to flush the system out when i got water in the oil. I'm gonna change it again and put 15-40 in to see if that helps the situation, Any ideas appreciated.