A/C refrigerant carries heat. A/C oil lubricates the compressor and helps protect its moving parts. Using the correct oil type and quantity is an important part of reliable automotive A/C service.
What is PAG 46?
PAG stands for polyalkylene glycol. The number 46 identifies a viscosity grade, not the amount of oil to add. PAG 46 is specified for many automotive A/C compressors, but it is not a universal oil.
Match the oil to the vehicle and compressor
Always follow the vehicle manufacturer's service information and the compressor manufacturer's requirements. PAG oils come in different grades and formulations. Refrigerant type alone does not establish which oil is correct, and oils should not be mixed or substituted without explicit approval.
Hybrid and electric vehicles may use electrically driven compressors that require a specific electrically insulating oil. Ordinary PAG oil must not be used unless the manufacturer expressly specifies it.
Too much or too little oil causes problems
Too little oil can damage the compressor. Too much can reduce cooling performance. A routine refrigerant recharge does not automatically require adding a full oil charge. The amount needed depends on the system's specified total capacity, oil already present, oil lost, and components replaced.
Keep moisture and contamination out
PAG oil absorbs moisture from the air. Keep containers tightly sealed and use clean service equipment. Oil exposed to moisture, dirt, or the wrong lubricant can compromise the system.
Oil during repairs
A replacement compressor may arrive with oil already inside, but that does not guarantee the quantity matches the vehicle's requirements. A technician must check the supplied oil and follow the manufacturer's balancing procedure. Compressor failure may also require contamination cleanup and replacement of affected components.
This guide explains the basics, not a vehicle-specific oil specification. Do not add oil by guesswork.
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