Please do yourself a favor and use ester oil. It is compatable with both r12 and r134.

The new compressor usually is pre filled, so you dump the oil out, and cycle ester oil through it. You dont have to flush it or anything, just get as much out as you can.

The good thing about ester oil is if for some reason you ever spring a leak, and are in a pinch, you can evac and recharge with r134. mineral oil removes the luxury and gives no real benefit.

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Eugene

10 E63 AMG
93 300te 4matic
07 BMW X3
14 Ford F-150 Fx2