Oil Used in R-134a-Charged Systems:

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A synthetic oil is used, which is totally different than the mineral-based oils used in Freon(R) R12 systems.

R-134a systems require Polyalkylene Glycol lubricants, often referred to as "PAG" oil. Use of R-12 compressor oil in R-134a systems will cause the compressor to seize and fail. The R-12 mineral oil does not stay in solution in R-134a. In addition, R-134a compressor should not be used in an R-12 system. Long term damage and corrosion will result.

The GREEN R-134a system labels, usually located near the top side of the fan shroud in the engine compartment, will display the refrigerant requirement for R-134a systems. An example is illustrated.

R-12 systems will have a BLACK label in a similar location.

Fig 1: Identifying Refrigerant Requirement Label For R-134A Systems

Courtesy of BMW OF NORTH AMERICA, INC.

PAG oil should only be stored in its original container, and sealed as tightly as possible. PAG oil is totally devoid of moisture when packaged, and will absorb moisture readily (hygroscopic) if exposed to the atmosphere, rendering it useless. Dispose of all extracted lubricants from A/C systems. Never reuse old compressor oil. Contaminated PAG oil should never be added to the air-conditioning system, and old PAG oil is typically contaminated with moisture. R-134a is even more sensitive to moisture contamination than R-12 systems, and because of the desiccant material change (refer to "Receiver-Dryer"), the capacity per volume of the receiver-dryer is typically less.

See T.R.I. 64 01 92.

PAG oil may be obtained from BMW of North America.

BMW Part No. 82 11 1 468 042.