We've used MP39 since the R-12 phaseout, same with HP80. Both work very well, with any oil in short coupled applications. 134A has been nothing but a nuisance with it's low capacity, and my habit has been to remove the 134A and replace it with MP39 when I do repairs on small equipment.

Both however are getting very expensive here in Canada. HP80 is more than double 404A and MP39 is almost three times 134a.

What are you folks using as a drop in replacement? I don't mind using 404A, it seems to work well, but I don't want to use 134A. And I'd need something that isn't oil dependent.