I'm working on an old single door traulsen reach in cooler. Not sure of the model number at this time. The unit was originally operated with R-12. When I got to it recently the compressor was found with a locked rotor. The compressor installed in it at this time is an Embraco FFI 12HBX. My research indicates that this is an R-134a compressor that contains iso 22 POE oil. I have no clue as to what refrigerant is in the unit at this time. Question I have is, when I replace this compressor should I get the same Embraco and attempt to use R-134 or get a compressor that contains AB oil and use mp 39 which is what I've done in the past with the removal of an R-12 compressor.