 re: newbie
I've had my f350 crew cab drw for nearly two years now. I bought it used also. Do you have the 7.3 turbo diesel?
I'd stick with a diesel oil, preferably the one that's been used in the engine since the thing was new. Look for an oil change sticker or in the owner's manual for recommendations. I'd ask several "experts" AND get the cost of a diesel oil change using syn oil before getting one done, assuming you've got the diesel engine.
Secondly, I'd change the fuel filter, air filter, and have the tranny fluid checked. Again, check the owner's manual for the recommended frequency of tranny fluid change along with any filters, o rings, etc. that are part of the job. I'd go to a certified shop for that job. Good luck. Ok and check the inner tire pressure on the dually axle along with the spare tire's pressure. You'll have to have an angled head pressure guage for the rear tire check. Good luck and hope this helps. | 
