Drier Core Crap

I'm baffled! Got refrigeration units using R-404a and over a period of about a year or so, or less, the drier cores stop up causing of course, low suction faults. Yes, units, not just one. The compressors are semi-hermetic Copelands with oil coolers. Got direct expansion evaporators cooling CO2 (refrigerant in tubes - CO2 shell side). Not sure of the oil type right now but can get that information. Have replaced a few compressor over the years but not like "all the time". Refrigerant pressures average 10 psig. suction (10 degree superheat) with a discharge pressure averaging 250 psig. Even after a complete evacuation and recharge with liquid, same result later on down the road. I know 404 has to be added as a liquid (if refrigerant charge is low), however I was wondering if a system was operating low on refrigerant charge and the leak was say on the gas side of the system, could the refrigerant imbalance be such that would cause some reaction therefore causing this breakdown (trash) in the drier core chamber? At fist I thought maybe the CO2 was getting into the refrigerant system (through the low side @ 10 psig refrigerant pressure versus 240 psig. CO2 pressure) but figured if that was happening I would see an increase in refrigerant discharge pressure. Years back I actually took some of that "trash" to a lab and the results were "some king of organic materials". It doesn't look rusty but more like a pile of coffee grinds big and small! Any ideas? Oil is EMKARATE RL 32-3MAF.

Hi PLEH2EREH
Are they separate systems or one system with multiple compressors?
You said you have changed a few compressors over the years, how many?
What caused their failure?
Has someone added the wrong Oil in the past?
What type of oil cooler?
Regards
Paul

4 independent compressors, 4 independent condensers, with one chiller barrel (4 circuit) so each compressor is it's own circuit. Considering there are 8 compressors, the failure rate is low considering the number of years they been in service and the run time is practically 24/7. The ones that did fail I believe were grounded. The new compressors come charged with oil, of course, but the oil did get changed with a compatible brand years back. Oil cooling is nothing but a factory add on that mounts on top of the compressor with a fan. Thanks for the reply PaulZ.