Changing to R-134 is expensive, but it will set you for the future. And the only problem with replacing yours is re-charging it, R-12 is expensive($30-50/lb). I just got 2 compressors from some people on this board, and they are both fairly good. I got two so I could have one re-built and I think I'm going to change to R-406. It runs with the same oils, same compression, same drier, gives 4-10 deg. cooler vent temps than R-12 and is about the same cost as R-134. I don't know how other people on this board feel about it, but I think I'm going to give it a try. Just my $.02,