[swissarmychainsaw]

I need to add about 3 oz of PAG oil to this system.

I arrived at that number by looking at the manual and talking to the sales/tech, the original system (with dual AC!) had 3 oz more then the since evap system.

So assuming the compressor has enough oil in it for a single AC system, we then will add 3 oz for a dual.

How should I add the oil?

I need to pull a vacuum on it anyway, so it's open, now.

I'm seriously considering opening one of the rear lines and just pouring 3 oz in.
Considering the rear lines are 15 feet long, I don't think it should be a problem.