Hi, I have a 85 635csi with a Bosch compressor.My good friend in Florida wants to change the system over to R134.He has done it many times and says that the system will work fine.He said it just takes a little longer to cool down.My questions are: Can we drain and re use the compressor? He wants to change the drier and lines,are they needed He said that the cost of R 134 Vs R12 even if the compressor can't handle it will save me money in the long run. I would love to hear from people who have done this. TIA Chip