PAG 46
You would need to add pag oil to system if you lost some such as when replacing the compressor, condensor, receiver dryer, evaporator or a blown hose. Replacing any one of those items you would add 1 to 2 oz of oil into each item during assembly. You didn't mention what vehicle you have but most systems use aprox 8 to 10 oz of oil for the entire system if it was brand new and bone dry. If you want to add oil because you want to, you can purchase a can of refrigerent with oil and suck it in thru the low side with pump running.
You should be able to ask at the autoparts store that the rebuilt compressor came from. Usually a system without rear ac has 8oz. of oil in it if the whole system was evacuated. You need to add at least a couple onces of PAG oil (probably PAG 150 for yours, but confirm it first) into the suction side of the compressor before you install it, then turn it on the clutch end and let it stand for a few minutes to lube the internal front seal. After that install it and once the lines are connected you must rotate the compressor (make sure you are rotating the compressor and not just the clutch) about 10 times to clear the oil out. If you have any trouble adding the oil to the compressor you can rotate it as you add it to pull it in also. You then should have replaced the orfice tube and accumulator/receiver/dryer anytime you replace a compressor and you will add a couple onces of oil into the accumulator/receiver/dryer as well before you install the new one. They both are cheap parts normally. If you replaced the condensor then you need to add a few onces oil into the new one as well. I dealership might be able to tell you more if you ask the parts or service dept. or your local parts stores etc...
PAG
You will use a PAG 46.
new o-rings coated with A/C PAG oil
8 oz of PAG 46
8 oz. of PAG 46, or PAG 100, or PAG 150 the numbers mean higher the number the thicker the oil. Thicker oil is better in high temp. situations..... p.s. 8 oz. of oil + 2 12 oz. cans of 134a. (if it is completely out)
It depends on the compressor. Consult your local auto parts store for the correct oil. It could be 46, 100,150 PAG or a Hybrid POE oil.
PAG oil goes in the air conditioner compressor. It is added in the same place as the refrigerant. However, this oil must be added before the lines for adding the refrigerant are put in place.
PAG 46
Typically Pag 46, and about 30z. At least that's what it was for my 2000.