Used in very-low-temperature refrigeration systems, typically the low stage of a multi-stage system. R508B has properties similar to R503 and can be used to replace either R13 or R503 in an existing system. The discharge temperature does not increase significantly compared to R23. POE lubricants should be used, and it may still be necessary to charge hydrocarbon oil additives to ensure proper oil return. Check with OEM for specific oil and charging recommendations.