I've made an appointment for next week to get the R12 evacuated from my system so that I can get started on this project. I found this good tutorial for replacing the W126 expansion valve:
Removal and Replacement of Expansion Valve
One of the final steps is to lubricate the o-rings with the same oil used in the compressor and drier. Which oil should I use? All of the PAG oil that I've seen on line is for r134. I need something that comes in a bottle. I'll be replacing the drier too, how much oil goes in there? Thanks