Mine leaks about 12 oz. per year (have to put in a can at the beginning of each season). If it is leaking from the evaporator, I'm in no hurry to do this job. I prefer paying about $35/year for R12. I hope it never gets worse...

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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