I am thinking of switching oils and Rotella is what I would like to run. The thing is, my owners manual calls for a 5w30 weight oil. It is a Ranger with the 4.0L SOHC. Where I live in Nebraska, we get temperature extremes. It can be 100 degrees in the summer and it can be below 0 in the winter. Is that 40 weight oil at operating temp going to be too heavy? Is anyone else running Rotella T 5w40 in there Ranger? Thanks!