OK...here's where the opinions start flying!.I had the dealer change my oil 'n filter on the '10 F350 using M/C 5W20 from the bulk barrel.I asked the mechanic for the SAE service data on the oil...they did'nt know.I expect it was C4.The use of 5W20 supposedly allows for a slight increase in mpg,in addition to quicker oil flow on cold startup.
So,then I asked about using Mr Moly which I've used for years,also marketed under names like Calgard,Molygard and others.I swear by it,after having used it initially on VW flat 4's,aka hiltler's revenge....to find it reduced wear,and gave considerable upper cyl and valve lubrication,adding to reliabiliy and longer life.
The Ford mechanic then said the newer oils (M/C 5W20) don't need additives,and that moly could cause problems..he was'nt sure.
The '10 5.4 SOC,3 valve motor IS different in design and configuation than the 351 Windsor,that I know so well,but I think oiling either makes little difference...
Wadd'ya all think....