Contamination Of Compressor Oil
WARNING: This page is about a different car, the 2002 Isuzu Axiom. However, it is still accessible from the selected car via links, so may be relevant.
Unlike engine oil, no cleaning agent is added to the compressor oil. Even if the compressor runs for a long period of time (approximately one season), the oil never becomes contaminated as long as there is nothing wrong with the compressor or its method of use.