Originally Posted by Piolet

The oil change you can do yourself if you are even half way mechanically capable.

Loosen the oil filter cap, the filter will come out attached to the underside of the lid. Remove the filter, and the o-ring around the lid. Clean the lid. Dip the new o-ring in some clean oil and put it on the lid. Snap the new filter up into the base of the lid. Screw the lid back in and don't over tighten.

Under the truck unscrew the oil drain plug. Let the oil drain into a collection pan and bring it to recycling. Clean the plug and put it back in. Buy 15 quarts of the correct oil (which oil to choose is a whole other thread. You won't go wrong with Shell Rotella T-6 5-w40 or Delo 400 LE 5w-40, but there are others). Buying 4 x 4 gallon jugs is better value than a load of 1 quart bottles.
Pour 13 quarts in the oil filler spout. Give it a few minutes and check the dipstick. You may find that 13 quarts does it for your engine, maybe it'll be 14, 14.5, maybe it'll be 15. Because of the high pressure oil system each engine can be a little different. Start the engine check for leaks.

You'll save yourself a load of cash and you'll know it's done right.