After recovering refrigerant and performing component service/replacement in an A/C system, any oil lost during the recovery process must be replenished. GM-50744 is used to inject oil into R1234YF A/C systems that use PAG oil. It is critical that POE oil used in electric compressor systems and PAG oil not be intermixed, so specific oil injection hoses for PAG and POE are required. Individual injection hoses help assure that no cross-contamination occurs. A large, durable tag wrapped around the GM-50744 hose clearly denotes it is only for R1234YF PAG oil A/C systems. Use with GM-45037 A/C Oil Injection Kit. For R1234YF POE oil systems, use the GM-50745 Oil Injection Hose.