Hi all, looking for some input on oil for a new 2020 F450 diesel oil. This is the new uprated 6.7 with the 10 speed and 4:30 gears. I ordered it in Dec. and it came in Mar 2nd, right before the plants closed. I bought it to pull a 43 ft 16K pound plus 5th wheel, my future retirement home. It will not see much towing for the next few years, maybe a 1000 miles a year towing and it is not my daily driver. I know I will get all kinds of recommendations of brands but I really want to stick to Motorcraft diesel oils. My main question is will the factory installed 10W30 be ok for now or should I go the 5W40 synthetic? Owners manual recommends 5W40 for severe use which includes towing over 1000 miles per oil change which I won't be doing until down the road. This truck brand new gets 18.5-19.5 mpg on a road trip, very nice with 4:30 gears on the 10W30. Thoughts oh wise ones?