I am going to charge my A/C system on my FJ-62 but the system has been open to the elements for a while now. I have a new dryer, and all the O rings, but I would like to replace the compressor oil. I plan on draining all the oil curently in the compressor (normally I would just replace the old oil with the same amount of oil as I drained out but I am not sure if that amount has not changed since I opened the system) Does anybody know what the correct amount of oil to add to a compressor that has been drained? I am not interested in converting to R-134a because I have enough R-12 to last me a while, before anyone suggests that. And I have all the proper equipment to do the job.