EDC Oil Type

Been looking thru past threads for an accurate answer but have not found what I am looking for. I finally found a Sanden 508 with the removable plug on the top (R12 type) on a Mazda B2000 (brackets included) but am trying the figure out what type of oil to run in the compressor? and how much?

From what I have read on other threads (mostly from Gravity5), this model of EDC does not need an external oiler to function correctly.

If oil is added to the plugged opening on the top, what would be considered to full, if that is even possible?

I believe that you just fill that up where the plug is until its full and check it often because they use oil when there running alot. Ive also heard of people doing a grease mod to them where a grease zerk is installed where the plug is and its just pumped full of grease.

my girlfriends dad does hvac he could possibly know ill ask him tomorrow