Refrigerant Oils
Use only new, moisture-free refrigerant oil in A/C systems. Refrigerant oil is highly refined with a very low moisture content. Oil container must be tightly closed when not in use, or moisture from air will be absorbed into refrigerant oil.
Refrigerant R-12 based systems use mineral oil, while R-134a systems use Polyalkylene Glycol (PAG) refrigerant oil. Using a mineral oil based lubricant with R-134a systems will result in A/C compressor failure due to lack of proper lubrication.
Different compressors have different lubrication requirements and use different specified Polyalkylene Glycol (PAG) refrigerant oils. Use only specified PAG refrigerant oil for the appropriate system and A/C compressor. Always check the underhood A/C specification label or A/C compressor label before adding refrigerant oil to A/C compressor/system. The following types of R-134a refrigerant oil are currently available.
Ford
On all models, use YN-12B PAG Refrigerant Oil (Part No. F2AZ-19577-AB).