R-438a (Mo99) 25 Lbs (R-22 Replacement)

MO-99 is a suitable alternative to R-22. I’ve found that the older condenser coils (from the 70’s, 80’s, and most of the 90’s) can’t dissipate heat well. This is due to the reduced surface area of aluminum fins and larger pipes. This poses a bit of a challenge where MO-99 has a higher discharge charge temperature. The higher discharge temperature doesn’t allow for the same volume of refrigerant to be filled in the condenser. The temperature of condensed refrigerant leaving the condenser is still pretty hot compared to ambient temperature.
On the other hand, larger condenser coils with smaller pipes and large surface area of aluminum fins, dissipate heat better and in these applications MO-99 is suitably matched. MO-99 works well on any compressor filled with mineral oil that originally was fitted for R-22 use.
As a side note:
I prefer R-407c as an alternative to R-22 on any compressor that is filled with POE oil, and is fitted for original R-22 use.

I used it for gas and it works so good

Good