PAG oil, or Polyalkylene Glycol, is a fully synthetic hygroscopic oil specifically designed for automotive air conditioner compressors. It is used in R-134a air conditioning systems to lubricate the compressor. When looking at PAG oil you will notice various numbers such as PAG46 or PAG100.
Similarly, what type of PAG oil should I use? With R-134a, there are primarily three different viscosities of PAG oil being used: PAG 46, which is the most popular viscosity oil; PAG 100, which is also common; and PAG 150, which is not often used, but it is still required for a certain compressor used in some GM vehicles from the 90s to the early 2000s.
Accordingly, can I use PAG 46 instead of pag100?
There is a difference in the viscosity (thickness) of PAG 46, PAG 100 and PAG 150. Plus, using anything other than the specified viscosity of PAG oil in systems that require it voids the warranty from many of those compressor manufacturers.
Do I need to add oil when recharging AC?
You normally do this when recharging the system after replacing one of the major components. This is tricky. The service manual normally tells you how much refrigerant oil should be added with each major component replaced on the AC system. Off-the-shelf cans sometimes come with refrigerant oil in them as well.
