Dear Guys ,

Usually for HCFC we use Mineral such as 3GS/4GS of SUNISO brand and usually for HFC we use POE such as SL100/SL68 of SUNISO oils and it is common in my country.
But these types of oils have low temperature working limited. It means we can use (If I do not do mistake) minimum to -50 or -60C.

For ultra low temperature freezers my friends use these types of oils but I know that they mix them with other material as solvent.
By this solvent they can use them to -120C in freezers.

Do you have any experience about this ? Or do you know which material we should use as a solvent by oil to use in case of ultra low temperature compressors ?

Thanks.