I use 30wt mineral oil.
It can be purchased by the quart at O'Reilly's after about an hour of convincing the clerk you are not looking for PAG or Ester oil.
4oz in the suction, 4oz in the discharge.

Rotate the compressor by hand a few times to lube the pump for initial startup.
Drier always goes on last and do it quickly with minimal exposure to outside air.
Get a vacuum pump on the system ASAP.
Don't forget new O-rings throughout the system, unless you like adding R12 a lot. LOL

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1991 F250 super-cab 7.3 IDI. (rebuilt by me) Banks Sidewinder turbo, hydroboost brakes, new IP and injectors.
2003 S430 - 107K
1983 300SD - Tanoshii - mostly restored ~400K+.
1983 300SD - Good interior. Engine finally tamed ~250K.
Monark Nozzle Install Video - http://tinyurl.com/ptd2tge