This is not a model-specific question:

In r134a systems running PAG oil:

When evacuating the system to replace components, it is possible to get a lot of oil out of the system if the High side is opened up. (Yes, I have recovery cylinders, and everything).

Given that PAG absorbs moisture over time, and may get dirty in operation, is it desirable to take steps to ensure that the maximum possible amount of existing oil in the system is replenished?

-Or, is this not important when the receiver/dryer/accumulator is being replaced. Will the dessicant and filter make the oil "good as new"?

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1986 300E 5-Speed 240k mi.