it took me a hell of a lot of research to get the same information you got in a 5 min conversation frank!
as you say, the machine doesnt remove the oil on a re-gas, it introduces a very small amount. new components need to be filled with pag 46 to the amount stated in the fsm. 2 floz is a good general rule of thumb for any system. i have said this a number of times when people have fitted new condensers, dryers etc and it has fallen on def ears. maybe because when they go for a re-gas they are told the machine does it automatically. (as i was) it doesnt, 8g was added in my case which is no where near enough, im presuming the operator, tech, engineer, operative, etc etc is taking this as there is enough oil being added to the system.