My respoinse was to bauble not to you.
(bolding mine)
Now maybe I’m an idiot here (after all I have only been working on cars for about 40 years) but how in the hell do you replace o rings in an A/C system without opening the system to the outside air? 
FWIW there should be no need to remove the R-12 vacuum oil, just add the ester oil (as I mentioned in my first post)