I just re-read your first post. If you are converting, you definitely need to blow out since you need to remove ALL the old oil which isn't compatible with R134a. I'm sure others will say you're OK as long as you get most of it. But you really should remove it ALL.

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08 W251 R350
97 W210 E320
91 W124 300E
86 W126 560SEL
85 W126 380SE Silver
85 W126 380SE Cranberry
79 W123 250
78 W123 280E
75 W114 280