I dont know much about the 4.7 liter engine as I have only had this truck a week, but from what I am hearing about it there is somewhat of a sludge problem. I read somewhere that small oil ports are what the cause of this is. Would this be the same reason the Ford 4.6 liters were burning up, and why Ford specified 5w20 to correct? What I am trying to find out is would it be of any benefit to run 5w20 in this 4.7 liter to try to combat the sludge issue? Thanks........