Here are some specs from the repair manual:
A/C system oil: VC-46 PAG oil. For some reason the diesel A/C comprssor takes different oil than the gas engines. This may be when running the O.E.compressor
A/C Clutch Air Gap: 0.35 - 0.75 mm (0.014 - 0.030 in.) 5.9L engine
The TOTAL amount of oil should be listed on the A/C service sticker on the radiator support. MAKE SURE that you know if the REPLACEMENT compressor was pre filled with oil or not.
Lets just say the system takes 8 oz of oil. THIS IS JUST FOR EXAMPLE. 4 to 5 oz goes into the compressor, 2 oz goes into the receiver drier and the condensor gets 1 oz of oil. After I had my system all sealed up but NOT charged, I turned the compressor shaft, by hand several revolutions to make sure the compressor wasn't hydro locked. You can do this by putting a socket on the securing nut that holds the compressor clutch on the compressor input shaft and turning it with a ratchet the direction it is supposed to turn when it is running. Charge the system with the indicated amount of R-134A after a deep evacuation. Run the vacuum pump for at least 1 hour.
With running my A/C on re-circ, I get 40 fegrees F out of the center vent! Better than when it was new.