what are you guys running for oil? I was going to go with the filter maintenance kit from genos '03-'07 Dodge Diesel Filter Maintenance Kit - FLEETGUARD-Geno's Garage but synthetic or non? I am pretty set on rotella, was looking at the 5w40 a lot because it is a lighter weight in the cold so it is easier in the winter. what about 10w30? or does it not matter and just go with 15w40 non synthetic?