I ran Mobil TDT 5W-40 when I first bought the truck, but 4X $23.00 is too much for me. So now I buy whatever properly rated 15W-40 is on sale. I have 4 gallons of 10W-30 for the upcoming winter change. It was hard to start with 15W-40 this last winter.
Most of the truck forums strongly advise against extending OCI's in the 7.3 because the injection system uses the engine oil as a working fluid. Since that may be correct, synthetics can't be a good idea @ $90+ per 5K miles.
I have a Pure Power cleanable oil filter. It keeps the oil so clean that you can see through it even a month later. Taking is apart is a snap, clean it with Simple Green, blow dry, reassemble and install.
I expect to have the truck until I quit driving, because by all accounts the engine could go 500-700K miles. So, be vigilant with your fluids, and don't get too wound up with goosing the power. Then you will have a truck for about as long as you want.