It works as you stated...But unless you pump the compressor down with a transfer using a legal transfer unit of course,, You will get a tremendous amount of Oil & Refrigerant out thru the schraeder valve.
If you remove the oil charge from the oil seperator, about 3 gallons or so in a single seperator, you will need about 4 Five gallon buckets to catch this foaming brew...
After a whil;e when the entrained rfefrigerant has boiled off, you will end up with a total amount of about 3 gallons of oil...
On the Lil' YCAS compressor, if you fail to pump the compressor down to atmospheric pressure, you will need at least 2 Five gallon buckets to catch the foaming brew...
Whatever amount of oil you just lost, should be replaced or the Oil Seperator oil level will be low on oil....
That's "York L" Oil if memory serves me...(300Vis. Sunoco or whatever).
Putting it in on a cold day you almost need a grease gun..
Ain't "None" of us as smart as "All" of us..