About what I have been reading here dealing with engine longevity. I have a 2k3 Durango with the 4.7 liter motor. I want the best oil for it, but I am not sure which way to go for this motor. I have 5w-30 in it now but I would like to go to a 0w-40 or 5w-40 weight oil. I am planning on getting about 300,000 miles out of this engine before I consider getting another vehicle(besides my Audi). Would I be better off using a 0w-40 (M1 of course) oil year round or a 5w-40? Thanks in advance and I will let the oil masters speak now.