Re: AC Compressor oil
If you bought a new or re-built compressor, it should come pre-oiled.
Here is the fun part. Take your old compressor off and drain the oil out of it into a bottle and measure it. Then drain that same amount of oil from the replacement compressor and you should be good. It doesn't have to be precise but it should be close. A little too much oil is better then too little.
The system oil capacity is 4oz but not all of that sits in the compressor. It sits throughout the A/C system.
If you do need to add the oil yourself (new compressor didn't come pre-oiled), I believe Pag46 is the stuff you're after. Same deal though, drain the old compressor and then add that much oil to the new one.
If you're unsure of the amount of oil in the system, just remember, too much oil is better than not enough. Too little and you risk of destroying the new compressor, too much and your A/C may run a few degrees warmer.