I have a 04 F250 PSD with 84K and I have wrote on here before about oil changes, brands and intervals. I have always used mastercraft 15-40 and will be getting a 40ft RV weighs 11K empty, any recc's for oil or oci's? Things to watch out for or be careful of? The RV will not be empty and I will probably be close to the 12.5-13K limit for the truck. Makes me a little nervous as I purchased the truck to pull a boat and I always like to stay 70% or under of max tow for longevity sake. Any added protection you guys know of? I sure would like to have a truck in a couple years!