FR12 is one of the dozens of snake oil refrigerants that are on the market.

In my shop I have two recovery/recycle machines, one for R12, and one for R134a. I will not under any circumstances use any other refrigerant. I also will not use 134 in an R12 system until after losing the argument about why it should not be done.

These snake oil refrigerants are causing more problems than anyone that uses them realize. Not only are people often breaking the law using them, as previously stated in this thread, they are being very shortsighted.

You are wise to stay with R12.

Good luck,