ES-12 does not contain oil. If your system has been charged more than once in the last several years, the refrigerant will evaporate and leave the oils behind. If you do charge the system while under vacuum, your not going to get the coldest air possible because the evaporator will freeze up to fast!

ES-12 is TOO efficient for most systems and when the freeze up starts, your compressor will cylce on and off leaving you getting cold, then hot, then cold, then hot.....see? ES -12 can have the performance characteristics of R22, it can deep freeze really fast.

There is no way to drain out the excessive oil without draining the entire system. You would need to recover the refrigerant and then drain out the oil.

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The Greatest Arizona Senator ever, Barry M Goldwater. I hope you can see from heaven how much you are missed.