Don, according to my manual the system holds 950 grams (or about 200ml) of mineral oil in the original R12 system. The evaporator holds 50 ml, the receiver/dryer 90 ml, the condenser 20ml, and the pipe another 20ml with the remaining 20ml scattered throughout elsewhere. You are supposed to place the oil in the component replaced in the correct quantity, although I imagine that placing it in the condenser or pipe or accumulator might work too. The replacement oil should be ester for R134 systems.