I have had extremely good luck with R409a and R408a when doing retrofits. I am wondering if anybody has tried any interim refrigerants and would share their experiences. I know I would be interested in anything helpful, tips to watch for etc.

I used to do tech support and listened to alot of guys complain about POE oils clogging systems etc. I too have worked with the POE oil systems and so-far so-good. I always draw a deep extended vacuum at least down to 100 microns preferably deeper. Sometimes it is tempting to just hit 500 blow a charge in it and run but so-far I have kept myself from doing it.