Just my experience. I tried ES12A in my 84 500SEL and was never able to get it to cool any better than 134. I sent E-mail to Envirosafe and they said it was because I evacuated the system before I charged it. If I wanted to evacuate then I should use ES12 Industrial. I let all the ES12A out and charged it starting at NO vacuum and it still didn't work any better. I did a deep evacuation, recharged with Freeze 12 and all is good again. I admit it takes a while for it to start cooling but is acceptable in NC. I have Freeze 12 in my 91 300D and it works OK there also. I'm sorry but I can't justify $600 to $800 for a 30 lb cyl of R12, or $45 to $50 for a 12 oz can. That is the going price here in NC. I know you can get it cheaper in Tex but that is probably because you are closer to the Mexican border.
Paul

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84 500 SEL (307,xxx miles)