So.......I bought 4 jugs of 5-40 oil for the diesel truck. When I go to use it...3 jugs are 5-40 and one is 0-40. Three jugs get an oil change done on the truck. So the truck is done but I'm looking for where I can use the remaining jug. I have no idea on why we use whatever oil in an engine. Can I run 0-40 synthetic in the 4.0litre?