Hello everybody:
I am new on this forum. I drive a MB 1985 300D Turbo, 123.
Mileage: 179,000.

I did mine using a similar kit purchased from K-mart for about 29.99( Interdynamics). It works well but I have to add a can or two every year. But Its still cheaper.
My advice, If you dont have a leak its good Idea to have a deep vacuum done to remove all old R-12 and air/moisture traces etc.
Then recharge with new R-134a kit. This I am told improves the life and eficiency.

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One penny saved is three penny earned.

1985 300D Turbo 179,000miles